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BY  1HE  SAME  AUTHOR. 


LIMES,  HYDRAULIC  CEMENTS  AND  MORTARS, 

CONTAINING 

NUMEROUS  EXPERIMENTS  CONDUCTED  IN  NEW  YORK  CITY. 
Fifth  Edition,  with  illustrations,  8vo,  cloth,  $4.00. 


OFFICIAL  REPORT  OF  OPERATIONS 

AGAINST  THE 

DEFENCES  OF  CHARLESTON  HARBOR,  1863. 

COMPRISING 

THE  DESCENT  UPON  MORRIS  ISLAND,  THE  DEMOLITION  OF 
FORT  SUMTER,  AND  THE  SIEGE  AND  REDUCTION 
OF  FORTS  WAGNER  AND  GREGG,  WITH 
70  LITHOGRAPHIC  PLATES, 

VIEWS,  MAPS,  ETC. 

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SUPPLEMENTARY  REPORT  TO  THE  ABOVE. 

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COIGNET  BETON,  AND  OTHER  ARTIFICIAL  STONE. 
Illustrated  by  9 Plates,  Views,  etc.,  8vo,  cloth,  $2.50. 


ON  STRENGTH  OF  THE  BUILDING  STONES 

IN  THE  UNITED  STATES. 

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• ca 


A 


PRACTICAL  TREATISE 


ON 

ROADS, 

TREETS,  AND  PAVEMENTS. 


BY 

Q.  A.  GILLMOEB,  A.  M., 


Lieut.  Col.  U.  S.  Corps  op  Engineers,  Brevet  Major-General  U.  S.  Army. 
Author  op  “Limes,  Hydraulic  Cements,  and  Mortars,”  “Beton 
Agglomere  and  other  Artificial  Stones,”  “Report  on 
Strength  op  Building  Stones  op  the  United 
States,”  &c .,  &c. 


SEVENTH  EDITION 


NEW  YORK: 

D.  VAN  NOSTRAND  COMPANY, 

23  Murray  St.  and  27  Warren  St. 

1890, 


i>.  VAN  NOSTKAIft1 
1876. 


U.  b 


PREFATORY  NOTE. 


In  the  preparation  of  the  following  pages  a few  leading 
objects  have  been  kept  in  view  by  the  author. 

First.  To  give,  within  the  compass  of  one  small  volume, 
such  descriptions  of  the  various  methods  of  locating  country 
roads,  and  of  constructing  the  road  and  street  coverings  in 
more  or  less  common  use  at  the  present  day,  as  will  render 
the  essential  details  of  those  methods,  as  well  as  certain  im- 
provements thereon  of  which  many  of  them  are  believed  to 
be  susceptible,  familiar  to  any  intelligent  non-professional 


Second.  To  make  such  practical  suggestions  with  respect 
to  the  selection  and  application  of  materials,  more  especially 
those,  with  the  properties  and  uses  of  which  builders  are 
presumed  to  be  the  least  acquainted,  as  seem  needful  in 
order  to  develop  their  greatest  practical  worth,  and  realizo 
their  greatest  endurance. 

Third.  To  institute  a just  and  discriminating  compar- 


now  competing  for  popular  recognition  and  favor,  undei  the 
varying  conditions  of  traffic,  climate,  and  locality,  to  which 
they  are  commonly  subjected. 


reader. 


ison  of  the  respective  merits  of  the  several  street  pavements 


Q.  A.  G, 


New  Yoke,  March  1, 1876. 


nni.ijivt  vmiMii' 


TABLE  OF  CONTENTS. 


CHAPTER  I. 

LOCATION  AND  GRADES  OF  COUNTRY  ROADS. 

PAG* 

Considerations  governing  location. — Elementary  principles  to  be 
kept  in  view. — Reconnaissance. — The  Aneroid  Barometer. — 
Advantages  and  manner  of  its  use. — Surveys,  maps  and  de- 
scriptive memoir. — Selection  and  location  of  line. — The  adop- 
tion of  the  shortest  line  seldom  practicable. — Questions  of 
expediency  are  to  be  considered. — Maps  of  contour  lines. — 
Parallel  cross  sections  of  route. — Grades. — Tractive  force. 

— M.  Morin’s  experiments. — Undulating  grades. — Maximum 
and  minimum  grades. — Statical  resistances  on  grades. — Sir 
John  Macneill’s  formulae  for  dynamical  resistances. — Mr. 
Law’s  table  of  same. — Increase  of  resistance  on  ascending 
equals  the  decrease  on  descending  the  same  grade .1  to  34 

CHAPTER  II. 

EARTHWORK,  DRAINAGE  AND  TRANSVERSE  FORM  OF 
COUNTRY  ROADS. 

Excavations  and  embankments. — Computations  of  same. — The 
lead. — Increase  in  volume,  or  “ growth  ” of  excavated  earth. — 
Moving  earth. — Completed  map  and  specifications. — Fixing 
the  line  on  the  ground. — Side  slopes  in  cuttings. — Their  treat- 
ment when  infested  with  springs. — The  drains  necessary. — 
Other  precautions  to  insure  stability. — Cuttings  through  rock. 

— The  formation  of  embankments. — Embankment  slopes. — 
Methods  of  their  protection. — Hill  side  roads. — Sustaining 
walls  for  same. — Roads  along  rocky  hill  sides. — Roads  ovey 


0 


CONTENTS. 


marshy  and  swampy  grounds. — Same  over  deep  marshes. — 
Roads  over  tidal  marshes. — Protecting  and  draining  same  by 
dikes  and  sluice  gates. — Application  of  this  method  to  Jersey 
Flats.  — Side-cuttings.  — Spoil-banks. — Side  drains.  — Cross 
drains. — Cost  of  stone,  brick  and  tile  drains. — Surface  drains. 

— Covered  side  drains,  and  silt  basins. — Culverts  of  vood,  con- 
crete, etc.— Width  of  main,  cross  and  branch  roads;  of  the 
French  roads  ; of  the  Cumberland  road. — Transverse  form  of 
roads. — Catch  waters. — Tools  and  implements 35  to  75 


CHAPTER  III. 

ROAD  COVERINGS. 

The  object  of  road  coverings. — Best  material  for  same. — The 
basaltic,  doleritic  and  other  trap  rock. — Other  materials. — 
Earth  roads.— Construction,  maintenance,  and  repairs  of  same. 

— Corduroy  Roads.  —Plank  Roads. — Advantages  and  defects  of 
same. — Gravel  roads. — Directions  for  their  construction. — 
Screening  and  applying  the  gravel. — Road  rollers. — Good 
gravel  roads. — Inferior  gravel  roads. — Macadam  roads. — 
Practice  of  the  English  and  the  French  constructors. — Roads 
of  the  Central  Park  in  New  York  city.— Preliminary  tests  of 
stone  for  road  coverings. — The  stone  crusher. — Thickness  of 
the  road  covering, — Macadam’s  practice. — Applying  the 
broken  stone. — The  “ wings”  of  roads. — Telford  roads. — The 
Telford  sub-pavement. — Same  with  gravel  and  broken  stone 
on  top. — Rubble  stone  sub-foundation,  and  Telford  pavement. 

— Same  without  the  Telford  pavement. — Concrete  foundation 
with  gravel  and  broken  stone  on  top. — Foundation  of  rubble 
stone  and  concrete.— Shell  roads. — Charcoal  roads 76  to  106 


CHAPTER  IV. 

MAINTENANCE  AND  REPAIRS  OF  ROADS. 

Schemes  for  raising  and  applying  the  funds  not  discussed. — Ex- 
cellence of  maintenance  requisite  from  motives  of  economy 
alone. — Different  conditions  of  the  same  road  compared. — 
Relation  of  animal  force  to  traffic  on  different  roads. — Where 
traffic  justifies  the  construction,  it  exacts  the  thorough  main- 
tenance of  a road. — Broken  stone  roads  are  seldom  well  kept 
up. — Method  of  maintenance  by  minute  daily  repairs,  of  roads 


CONTENTS. 


? 


of  moderate  traffic. — Implements. — Whitworth’s  machine 
sweeper. — Street  sweeper  used  in  New  York  city. — A very 
soft  sweeper  necessary  upon  road  coverings. — Directions  for 
applying  the  new  materials. — Thick  layers  to  be  avoided. — 

The  process  is  properly  one  of  constant  patching. — Experi- 
ence of  the  French  Engineers. — Roads  in  the  Department  of 
the  Sartlie. — Lyons  and  Toulouse  road. — Tours  and  Caen 
road.— Method  of  maintenance  by  periodical  reconstruction. — 
Adapted  to  roads  of  large  traffic. — Practical  precautions 
necessary. — Relaying  and  rolling. — Material  to  be  sprinkled. 

— Determination  of  thickness  and  composition  of  road  cover- 
ing.— Relation  between  annual  wear  and  average  daily  ton- 
nage of  roads  in  the  Department  of  the  Loire,  and  in  the 
Arrondissement  of  St.  Etienne. — Curves  of  daily  tonnage  and 
annual  wear. — Ratio  of  wear  to  tonnage  not  constant. — Wear 
increases  more  rapidly  than  tonnage. — Necessity  for  using 
the  best  material  increases  with  the  tonnage. — Apportion- 
ment of  materials. — Maintenance  of  gravel  roads 109  to  136 


CHAPTER  V. 

STREETS  AND  STREET  PAVEMENTS. 

Functions  of  a modern  street. — Ancient  sewers. — Modern  sewers. 
— Necessity  of  subsoil  drainage. — Different  methods  of  secu- 
ring it. — The  object  and  essential  requisites  of  a good  street 
pavement. — Pavement  foundation  of  broken  stone  — Of  sand. — 
Of  cobble  stones. — Cobble  stone  pavement. — Old  road  cover- 
ings as  foundations. — Rubble  stone  pavement,  as  a foundation. 
— Concrete  foundation. — Foundation  of  rubble  stone  and  con- 
crete.— Sidewalks  and  sidegutters. — Curb  and  gutter  stones. 
— Pavement  of  stone  blocks. — Best  dimensions  for  the  blocks. 
— Different  methods  of  laying  same. — Special  methods  on 
steep  grades.  The  Guidet  stone  pavement. — The  Russ  and 
the  Belgian  pavements. — The  Nicolson,  Stowe  and  other 
wooden  block  pavements. — Treatment  of  wood  to  prevent 
decay. — Chicago  wooden  pavements. — Hydro-carbonized  brick 
pavements. — Asphalt  pavements. — Varieties  of  bitumen. — 
Description  of  natural  mineral  tar,  bituminous  limestone  and 
asplialtum. — The  mineral  tar,  called  also  asphaltic  cement, 
formed  by  uniting  two  or  more  bitumens.: — Proper  propor- 
tions of  petrolene  and  asphaltine. — Bituminous  limestone  pave- 
ments.— Concrete  the  best  foundation  for  same. — Old  pave- 
ments for  foundation  under  certain  precautions. — Heating 


8 


CONTENTS. 


the  asphalt  or  bituminous  limestone. — Method  of  applying 
the  same. — Importance  of  an  even  finish  on  surface. — Direc- 
tions for  making  asphalt  pavements,  without  the  asphalt  rock, 
comprising — (1)  The  preparation  of  asphaltic  cement — (2) 

The  powdered  calcareous  sand — (3)  Mixing  the  cement  and 
powder,  and  (4)  applying  the  mixture  by  the  first  method. — 
Asphalt  block  pavements. — Merits  and  cost  of  asphalt  pave- 
ments.— Asphalt  pavements  of  New  York  city. — Compara- 
tive merits  of  wood,  stone,  and  asphalt  pavements  as  to — (1) 
durability — (2)  first  cost — (3)  Cost  of  maintenance  and  repairs — 

(4)  Facility  of  cleansing — (5)  Convenience,  and  (6)  hygienic 
considerations. — General  conclusions .137  to  201 


CHAPTER  VI. 

SIDEWALKS  AND  FOOTPATHS. 

Concrete  footpaths. — Foundation  for  same. — Precautions  against 
upheaval  by  frost. — Proportions  of  ingredients. — Directions 
for  laying. — Treatment  of  surface  layer. — Squares  or  rectan- 
gles preferable  to  a single  sheet. — The  Scliillinger  pavement. 

— Deficient  in  compressive  strength  and  power  to  resist  frost. 

— Table  of  compressive  strength  of  Portland  cement  and  Ro- 
sendale  cement  Mixtures. — Beton  Coignet. — Asphalt  foot- 
paths.— Their  thickness. — May  be  made  with  the  asphalt  rock, 
or  with  bituminous  mastic. — Directions  for  making  bitu- 
minous mastic. — Extensively  used  on  public  works. — Method 
of  application. — Sidewalks  over  street  vaults. — Must  be  water 
tight. — The  precautions  necessary  to  secure  that  condition. — 
Brick  footpaths. — Foundations  for  same. — Flagging  stone  foot- 
paths.— Hudson  river  flagging. — Broken  stone  and  gravel 
footpaths. — For  parks  and  sidewalks  of  country  and  sub- 
urban roads. — Preparation  of  the  bed  for  the  material. — 
Tiles  for  sub-drainage. — Lower  layer  and  surface  layer. 

— Park  walks. — Transverse  form. — Sod-gutters  and  cobble 
stone  gutters. — Drainage  of  an  area  covered  by  a system  of 
walks. — Hand-made  concrete. — Mill-made  concrete. — The 
cubical  concrete  mixer,  and  manner  of  using  it .208  to  226 

CHAPTER  VII. 

TRAMWAYS  AND  STREET  RAILWAYS. 

Comparative  tractive  force,  on  stone  tramways,  broken  stone 
roads,  and  gravel  roads. — Definition  of  tramway. — Adapted  to 


CONTENTS. 


9 


all  kinds  of  vehicles. — In  common  use  in  southern  Europe. — 
Description  of  the  Italian  Tramways. — Their  cost  of  construc- 
tion, durability,  maintenance,  and  repairs. — Tramways  not 
adapted  to  the  crowded  streets  of  a city. — Double  track  tram- 
way.— Pavement  between  the  trams. — Pavement  of  selected 
stone  blocks  a good  substitute  for  a tramway. — Street  rail- 
ways.— Resistances  to  the  movement  of  cars  on  good  level 
rails. — Rule  for  calculating  the  same. — Street  grades  suitable 
for  street  railways. — Bleecker  street  and  Fulton  Ferry  line, 
New  York. — Drainage. — Construction. — Rails. — Stringers. — 
Cross  Ties. — Fastenings. — Pavement  of  horse  track. — Of 
street  on  either  side. — The  substitution  of  stone  and  iron  for 
timber. — Mechanical  motive  power  for  animals. — The  effect 
of  frequent  startings  upon  the  animals. — Mechanical  car  start- 
ers.— The  Crozier  car  brake  and  starter. — The  fireless  locomo- 
tive.— Table  of  the  cost  of  constructing,  maintaining,  and 
operating  street  railways  in  the  State  of  New  York,  and  in 
Massachusetts 227  to  252 


I 


i 

i 


PRACTICAL  TREATISE 


OK 

ROADS,  STREETS,  AND  PAVEMENTS* 


CHAPTER  I. 

LOCATION  AND  GRADES  OF  COUNTRY  ROADS. 

Considerations  Governing  Location. 

The  considerations  which  should  govern  the  Engineer  in 
locating  the  line  of  an  ordinary  wagon  road  are  (1)  the 
present  and  prospective  amount  of  traffic  over  the  road  ; (2) 
its  general  character,  whether  light  or  heavy ; (3)  the  con- 
venience and  necessities  of  the  community  tributary  to  the 
line  ; and  (4)  the  natural  features  of  the  country  through 
which  the  road  must  pass.  The  labor  of  the  preliminary 
examination  of  the  ground  will  be  considerably  lessened  by 
keeping  in  view  a few  elementary  principles,  viz  : (1)  that 
the  natural  water  courses  are  not  only  the  lowest  lines,  but 
the  lines  of  the  greatest  longitudinal  slope  in  the  valleys 
through  which  they  flow  ; (2)  that  the  direction  and  posi- 
tion of  the  principal  streams  give  also  the  direction  and 
approximate  position  of  the  high  ground  or  ridges  which  lie 
between  them;  and  (3)  that  the  positions  of  the  tributaries 
to  the  larger  streams  generally  indicate  the  points  o.f 
greatest  depression  in  the  summits  of  the  ridges,  and  there' 


LO 


HOADS,  STREETS,  AND  PAVEMENTS. 


fore  the  points  at  which  lateral  communication  across  the 
high  ground  separating  contiguous  valleys  could  be  most 
readily  made. 

Reconnaissance . 

With  the  aid  of  an  ordinary  map  of  the  country,  if 
reasonably  correct,  it  is  entirely  practicable  to  trace  upon  i t 
with  a sufficient  degree  of  accuracy  for  the  immediate  object 
in  view,  not  only  the  general  directions  of  the  ridges  or 
highest  ground,  but  also  to  locate  approximately  those 
routes  most  suitable  for  the  purposes  of  a road  across  the 
hills,  from  one  valley  to  another. 

Being  provided  with  the  information  usually  supplied  by 
maps  or,  in  the  absence  of  trustworthy  maps,  having  secured 
that  information  by  an  instrumental  examination,  the  topo- 
graphical and  other  characteristic  features  of  the  ground 
should  be  carefully  studied  by  travelling  in  both  directions 
over  the  several  routes,  upon  any  one  of  which  the  line  may 
be  located,  carefully  noting  down  for  future  comparison,  the 
distinctive  features  of  each. 

Aneroid  Barometer. 

If  the  line  passes  over  such  hilly  or  undulating  ground, 
that  considerable  differences  of  level  are  necessarily  encoun- 
tered in  its  location,  valuable  aid  may  be  derived  from  a 
pocket  Aneroid  barometer.  This  instrument  shown  in  sec- 
tion through  the  axis  in  Fig.  1,  consists  of  a flat  cylindrical 
box  A,  exhausted  of  air,  the  top  of  which  is  thin  metal  cor 
rugated  in  concentric  circles  so  as  to  render  it  quite  elastic. 
As  the  atmospheric  pressure  increases,  the  elastic  top  of  tin* 
box  is  forced  in  or  down,  and  as  it  decreases  it  is  forced  out 
or  up.  This  movement  of  the  top  of  the  box  due  to  changes 


ANEROID  BAROMETER. 


11 


in  tlie  atmospheric  pressure,  is  conveyed  by  multiplying  levers 
DE,  EG,  GII,  and  a small  chain  II  to  an  index  needle  NN, 
moving  over  a circular  scale  MM,  graduated  to  correspond 
with  the  standard  mercurial  barometer.  The  spiral  spring 
S,  by  its  tension  raises  the  long  arm  of  the  lever  DE,  when 
the  pressure  on  the  top  of  the  box  is  lessened,  thus  keeping  the 
short  arm  of  the  lever  constantly  in  contact  with  the  fulcrum 
C.  The  Aneroid  is  used  by  the  following  rule:  The  sum 
of  the  readings  at  two  stations,  is  to  their  difference,  as  55,000 
(or  twice  the  height  of  the  atmosphere  in  feet),  is  to  the  ele- 


vation required.  Thus,  if  the  reading  at  the  foot  of  a hill 
is  30.05,  and  at  the  top  29.44,  we  have  the  following  59.49  : 
0.61  : : 55,000ft.  : 564ft. 

By  the  intelligent  use  of  this  barometer,  the  scope  of 
inquiry  may  frequently  be  much  narrowed  at  the  outset,  and 
the  labor  and  expense  of  the  subsequent  survey  greatly 
abridged.  For  instance,  if  the  line  of  communication  is  to 
connect  two  valleys  by  crossing  the  high  ground  between 
them,  it*should  be  located,  other  things  being  equal,  in  the 
lowest  depression  of  the  summit.  A reconnaissance  with  a 
barometer  should  indicate  with  an  error  not  exceeding  10  tc 
15ft.  the  relative  altitude  of  the  several  summit  depressions, 


13 


ROADS,  STREETS,  AND  PAVEMENTS. 


and  therefore  the  best  location  of  the  route,  so  far  as  the 
question  of  grade  fixes  the  location.  The  average  of  sev- 
eral observations  with  the  barometer,  is  desirable. 

Surveys,  Map  and  Descriptive  Memoir. 

The  reconnaissance  having  been  completed,  and  the 
inquiry  narrowed  down  by  the  exclusion  of  the  least  prac- 
ticable routes,  preliminary  surveys  should  then  be  made  of 
the  several  trial-lines , with  a view  to  determine  their  length, 
direction,  and  position,  together  with  a longitudinal  section 
and  numerous  cross-sections  of  each  line.  All  this  should 
be  done  with  sufficient  accuracy  and  minuteness  of  detail  to 
form  the  basis  of  comparative  estimates  of  their  practicabil- 
ity and  cost.  Money  liberally  spent  in  surveys  entrusted  to 
skillful  persons,  is  wisely  spent,  and  offers  the  surest  guar- 
antee against  subsequent  mistakes  and  errors  of  judgment., 
Its  amount,  at  the  outside,  cannot  exceed  a very  small  per 
centage  of  the  cost  of  constructing  the  road,  while  the 
results,  judiciously  employed,  are  sure  to  furnish  innumer- 
able suggestions  for  lessening  the  cost  without  impairing  the 
excellence  of  the  communication. 

Map. 

The  data  obtained  from  the  surveys  should  be  carefully 
embodied  in  a map,  showing  with  considerable  detail,  the 
topography  of  the  country  embraced  by  the  several  trial- 
lines, the  exact  position  of  these  lines,  and  all  the  longitudi- 
nal and  cross-sections.  The  horizontal  scale  of  the  sections 
should  be  the  same  as  that  of  the  map,  while  the  vertical 
scale  should  be  considerably  larger,  in  order  to  show  clearly 
all  the  inequalities  of  the  ground.  With  a horizontal  scale 


LOCATION  OF  LINE. 


13 


of  500ft.  to  the  inch,  the  vertical  scale  may  be  only  20ft.  tc 
the  inch. 

Descriptive  Memoir. 

The  descriptive  memoir  should  give  with  minuteness  all 
information,  such  as  the  nature  of  the  soil,  the  character  of 
the  several  cuttings,  whether  earth  or  rock,  the  kind  of  rock, 
etc.,  etc.,  that  cannot  be  set  forth  on  the  map.  The  import- 
ance of  carefully  noting  in  the  memoir,  and  as  far  as  practi- 
cable upon  the  map  also,  all  variations  of  the  character  of  the 
cuttings  through  rock,  and  especially  of  maintaining  a strict 
distinction  between  cuttings  in  rock  and  cuttings  in  earth,  will 
be  admitted,  when  it  is  remembered  that  excavations  in  earth 
can  be  made  at  less  than  one-fourth  the  cost  of  excavations 
in  rock. 

Location  of  the  Line. 

“In  selecting  among  the  different  lines  of  the  survey  the 
one  most  suitable  for  a common  road,  the  engineer  is  less 
restricted,  from  the  nature  of  the  conveyance  used,  than  in 
any  other  kind  of  communication.  The  main  points  to  which 
he  should  confine  his  attention  are,  (1)  to  connect  the  points 
of  arrival  and  departure  by  the  shortest  or  most  direct  line  ; 
(2)  to  avoid  all  unnecessary  ascents  and  descents,  or  in  other 
words  to  keep  the  ascents  and  descents  within  the  smallest 
practicable  limits  ; (3)  to  adopt  such  slopes  or  gradients  for 
the  centre  line  of  the  road  as  the  kind  of  conveyance  used 
may  require  ; (4)  to  give  the  centre  line  such  a position  with 
reference  to  the  natural  surface  of  the  ground,  and  the 
various  obstacles  to  be  overcome,  that  the  cost  of  labor  for 
excavations  and  embankments  required  by  the  gradients 
adopted,  and  also  the  cost  of  bridges  and  other  accessories, 
shall  be  reduced  to  the  smallest  amount.”  (Prof.  Mah^n.) 


14 


ROADS,  STREETS,  AND  PAVEMENTS. 


Except  in  a flat  and  level  country,  it  will  seldom  be  prac- 
ticable to  adopt,  for  the  axis  of  the  road,  the  shortest  line 
between  the  points  of  arrival  and  departure.  Departures 
from  a straight  line  are  determined  by  a variety  of  consider- 
ations. In  crossing  a dividing  ridge  between  two  valleys, 
we  seek  a depression  in  the  summit,  in  order  to  avoid  expen- 
sive cutting,  or  the  alternative  of  steep  or  impracticable 
gradients  ; in  descending  a valley  longitudinally,  we  keep 
well  up  on  the  side  of  the  hill,  if  necessary,  to  avoid  bridg- 
ing the  ravines  and  secondary  water-courses  ; if  we  encoun- 
ter a swamp  or  shallow  pond,  we  can  frequently,  by  turning 
to  the  right  or  left,  entirely  omit  the  construction  of  an 
expensive  causeway  or  other  road  bed,  or  substitute  for  it  a 
short  bridge  over  a narrow  water-course,  with  easy  approaches 
on  either  side ; a stream  may  cross  and  then  re-cross  the 
direct  line,  forming  an  elbow  which  may  sometimes  be  turned 
without  greatly  augmenting  the  length  of  the  road,  thus 
avoiding  the  construction  and  maintenance  of  two  bridges  ; 
we.  may  turn  aside  and  even  bridge  a stream  in  order  to  get 
upon  that  slope  of  a valley  which  will  give  the  best  expos- 
ure of  the  road  surface  to  sun  and  wind  ; or  we  may  lengthen 
the  road  for  the  purpose  of  procuring  better  material  for  its 
construction. 

Questions  of  Expediency  to  be  Considered. 

Not  infrequently  other  questions  not  strictly  within  the 
province  of  the  engineer  claim  attention  to  such  degree  that 
although  a straight  line  between  the  two  termini  of  the  road 
may  be  the  best,  considerations  of  expediency  will  very  prop- 
erly prevent  its  adoption.  Intermediate  communities  and 
towns  contiguous  to  the  line  may  require  accommodation, 


QUESTIONS  OF  EXPEDIENCY.  1C 

and  whether  such  accommodation  shall  be  afforded  by  lateral 
branch  roads,  leaving  the  main  line  essentially  straight,  or 
by  running  the  latter  through  the  several  centres  of  busi- 
ness, will  have  to  be  determined  upon  principles  more  or  less 
independent  of  the  bare  problem  of  construction  and  main- 
tenance. For  example  take  the  simplest  case  of  three  towns 
A,  B,  0,  Fig.  2,  situated  upon  a uniformly  level  plain, 
where  the  cost  of  construct- 
ing and  maintaining  a line  of 
communication  will  be  di- 
rectly proportional  to  its  length.  Suppose  the  points 
of  arrival  and  departure,  A and  C,  to  be  120  miles  apart, 
and  that  B is  equi-distant  from  A and  C,  but  located 
20  miles  off  the  direct  line  AC.  If  each  town  sends  out 
20  tons  of  freight  per  day  to  be  distributed  equally  (10 
tons  to  each)  between  the  other  two  towns,  a simple  cal- 
culation will  show  that  with  a straight  road  AC,  between  the 
extreme  points  and  a perpendicular  branch  road  B'B  to  the 
intermediate  town,  the  daily  transportation  of  this  30  tons 
of  freight,  will  be  equivalent  to  transporting  1 ton  5600  miles, 
while  if  one  straight  road  be  built  from  A to  B,  and  another 
from  B to  C,  the  total  carriage  will  be  equivalent  to  convey- 
ing 1 ton  only  5060  miles.  The  difference,  (equal  to  540 
tons  carried  1 mile)  in  favor  of  the  lines  AB,  BC,  over  the 
lines  AC  and  B'B  is  borne  unequally  by  the  three  towns  in 
proportion  of  335  tons  to  B,  and  102|-  each  to  A and  C.  In 
the  case  stated,  it  is  for  the  mutual  advantage  of  all  the 
three  communities  to  locate  the  line  from  A to  B and  from 
B to  C.  But  the  conditions  would  be  different  if  the  great 
bulk  of  the  traffic  is  between  the  towns  of  A and  C,  For 
example,  if  those  towns  exchange  20  tons  per  day  with  each 


Fig.  2. 


16 


ROADS,  STREETS,  AND  PAVEMENTS. 


other,  and  only  2 to  3 tons  per  day  with  the  town  B,  then 
the  total  mileage  of  transportation  necessary  in  making 
the  interchange,  setting  other  considerations  aside,  would 
favor  the  construction  of  a straight  line  AC,  between  the 
terminal  towns,  and  a perpendicular  branch  line  B'B  to  the 
intermediate  town.  But  as  this  would  require  a greater 
length  of  road  by  13^  miles  (140 — 126^)  than  a continuous 
line  ABC  passing  through  the  intermediate  town,  the  ex- 
pediency of  building  and  maintaining  upwards  of  10  per  cent 
more  road  than  is  absolutely  necessary  to  connect  the  three 
towns,  presents  itself  as  a question  of  some  commercial  im- 
portance, and  before  adopting  the  longer  system,  it  should 
be  made  quite  clear  that  the  yearly  saving  in  cost  of  trans- 
portation will  be  more  than  sufficient  to  pay  the  interest  on 
the  first  cost  of  constructing  13|  miles  of  road,  as  well  as  the 
annual  expense  of  its  maintenance.  Except  in  extreme  cases 
where  the  two  towns  at  the  ends  of  the  line  are  large  in  com- 
parison with  the  intermediate  towns,  it  will  usually  be  found 
to  be  most  conducive  to  the  convenience  of  the  general  pub- 
lic to  run  the  line  through  all  the  principal  communities,  in 
preference  to  the  plan  of  communicating  with  the  intermedi- 
ate places  by  branch  roads,  which  might  necessitate  branch 
lines  of  wagons  and  coaches,  connecting  with  those  of  the 
main  line,  attended  by  all  the  usual  inconvenience  and 
expense  of  transferring  passengers  and  goods  at  the  points 
of  junction. 

In  the  general  case,  however,  the  road  will  not  traverse 
a level  plain  but  will  cross  hills,  ravines,  rivers,  and  other 
accidents  of  the  ground,  so  that  the  proper  solution  of  the 
problem  will  involve  a variety  of  considerations,  among 
which  the  engineer’s  ideal  of  a straight  and  level  liue,  tba 


COKTOtlU  Lttftts. 


1 


Wants  of  the  communities  to  be  accommodated,  and  econ- 
omy in  cost  of  construction  will  generally  be  more  or  less  at 
variance. 

As  it  should  be  the  first  business  of  the  engineer  to  make 
himself  thoroughly  familiar  with  the  character  of  the  coun- 
try adjacent  to  the  line,  for  some  distance  on  either  side,  all 
the  preliminary  field  work  should  be  directed  to  that  end. 

Contour  Lines. 

In  laying  out  important  roads,  and  especially  in  locating 
streets  in  towns  or  thickly  settled  districts,  where  the  ques- 
tions of  gradient,  drainage,  sewerage,  and  water  supply 
assume  special  importance,  it  would  be  well  to  place  the 
contour  lines,  or  curves  of  uniform  level,  upon  the  map. 
These  curves  represent  the  intersections  of  the  surface  of  the 
ground  with  a series  of  horizontal  planes  at  equal  distances 
apart,  of  say  3ft.  5ft.  10ft.  or  more — and  indicate  at  once 
to  the  practiced  eye  the  topography  of  the  country  which 
they  embrace.  We  give,  Fig.  3,  the  contour  lines  of  a small 
tract  of  country,  showing  a variety  of  natural  features,  such 
as  undulating  slopes,  steep  hill  sides,  ravines,  water,  and 
marsh.  Every  curve  represents  a level  line  traced  upon  the 
ground,  the  vertical  distance,  or  difference  of  level,  between 
the  curves  being  3 feet. 

Parallel  Cross  Sections. 

A survey  so  complete  as  would  be  required  for  mapping 
the  contour  lines  in.  the  manner  shown  in  Fig.  3,  is  seldom, 
if  ever,  resorted  to,  and  is  indeed  unnecessary  for  the  proper 
location  of  a country  road.  It  will  suffice  to  take  a series  o i 
cross  sections  parallel  to  each  other,  and  extending  a suffi- 
cient distance  laterally  to  embrace  the  width  of  the  country 


Fig.  3. 


8 8 8 


PARALLEL  CROSS  StiCTlOtfS. 


19 


under  examination.  By  plotting  these  sections  to  a scale, 
in  their  true  relative  positions,  all  referred  to  the  same  level 
or  datum  line,  it  will  be  easy  to  locate  the  axis  of  the  road 
properly  thereon,  and  to  estimate  the  quantities  of  excava- 
tion and  embankment,  provided  the  sections  are  taken  suffi- 
ciently near  together.  Their  distances  apart  should  of  course 
be  less  in  proportion  to  the  ruggedness  and  unevenness  of 
the  country.  Suppose,  for  example,  that  C,  D,  M,  N,  Fig.  4, 
represents  a portion  of  the  strip  of  country  under  examina 


tion  and  A,  B,  the  general  direction  of  the  road,  which  must 
be  located  somewhere  between  the  lines  C,  M,  and  D,  N. 
Having  run  the  several  lines  of  levels  C,  D,  E,  F,  etc., 
transversely,  and  at  least  one  line  A,  B,  longitudinally  so 
as  to  establish  a common  datum  line  for  all,  the  sections  are 
drawn  as  shown  in  the  figure.  As  a part  of  the  map  or  plan 
the  right  lines  0,  D,  E,  F,  etc.,  show  the  positions  of  the 
cross  sections,  while  they  are  also  the  datum  lines,  all  on  the 
same  level,  of  their  respective  sections.  Those  portions  of 
each  section  to  the  left  of  the  datum  line  represent  ground 
above  that  line  and  those  portions  to  the  right,  below  it,  and 


20 


fcOAbS,  STREETS,  AtfD  PAVEMENTS* 


a line  like  0,  P,  drawn  through  points  in  the  several  sections 
that  are  at  the  same  distance  from  and  on  the  same  side  of 
the  datum  lines,  will  show  the  exact  location  of  a level  line 
traced  on  the  surface  of  the  ground.  Hence  the  axis  of  the 
road  if  located  on  the  line  0,  P,  will  be  level,  while  upon 
the  line  Q,  S,  it  would  have  an  ascending  grade  of  ^ from 
Q,  to  E,  and  a descending  grade  of  from  E to  S. 

Having  completed  the  surveys,  and  prepared  the  map 
and  memoir  with  as  much  detail  as  possible,  the  engineer 
will  then  be  able  to  study  with  intelligence  the  relative  ad- 
vantages of  the  trial  lines,  and  to  establish  definitely  their 
location,  direction  and  gradients,  in  order  that  the  volumes 
of  excavations  and  embankments  shall  balance  each  other  as 
nearly  as  possible,  except  when  other  methods,  hereafter 
referred  to  would  lessen  the  expense,  while  the  cost  of  con- 
structing the  necessary  bridges,  culverts,  etc.,  shall  be  care 
fully  kept  at  the  minimum. 

Grades. 

Upon  common  roads  the  grades,  or  the  angles  which  the 
axis  of  the  road  should  make  with  a horizontal  line,  depend 
so  much  upon  the  kind  of  vehicle  employed  for  traffic,  the 
character  of  road-covering  adopted  for  the  surface,  and  the 
condition  m which  that  surface  is  maintained,  that  no 
empyrical  rule  can  be  laid  down.  The  grade  should  not 
be  so  great  as  to  require  the  application  of  brakes  to  the 
wheels  in  descending,  or  to  prevent  ordinary  vehicles  carry- 
ing passengers  ascending  at  a trot.  In  general  the  gradient 
should  be  somewhat  less  than  the  angle  of  repose , or  that 
angle  upon  which  the  vehicle  in  a state  of  rest  would  not  be 
set  in  motion  by  its  own  weight,  but  would  descend  with 


GRADES  AND  TRACTIVE  FORCE. 


21 


slow  uniform  velocity  if  very  slight  motion  be  imparted  to 
it.  The  grades  therefore,  suitable  for  any  road,  will  depend 
upon  the  condition,  with  respect  to  smoothness  and  hard- 
ness, in  which  the  surface  is  to  be  maintained,  and  hence 
upon  the  kind  of  road^covering  used ; and  as  the  force  of 
gravity  is  the  same  whether  the  road  be  rough  and  soft,  or 
smooth  and  hard,  steep  grades  are  more  objectionable  upon 
good  roads  than  upon  bad. 

Tractive  Force. 

Many  ingenious  experiments  have  been  made  at  various 
times  to  ascertain,  in  functions  of  the  quality  and  condition 
of  the  road  surfaces,  the  measure  of  the  tractive  force,  or  the 
force  required  to  overcome  the  resistances  which  oppose 
themselves  to  the  movement  of  a vehicle  along  horizontal 
roads  of  different  degrees  of  smoothness  and  hardness,  and 
covered  with  different  materials.  From  some  of  the  experi- 
ments of  M.  Morin,  conducted  for  the  French  government, 
the  following  general  results  were  deduced  : 

1.  The  force  of  traction  varies  directly  with  the  load  and 
inversely  with  the  diameter  of  the  wheels. 

2.  The  resistance  is  practically  independent  of  the  width 
of  tire  on  paved  or  hard  Macadamized  roads,  where  that 
width  exceeds  3 or  4 inches. 

3.  At  ordinary  walking  speed  the  traction  is  the  same 
for  carriages  with  springs,  as  for  those  without  them,  the 
other  conditions  being  the  same. 

4.  The  force  of  traction  increases  with  the  speed  upon 
paved,  or  hard  Macadamized  roads.  When  the  speed  ex- 
ceeds 2|  miles  per  hour  the  increase  in  the  resistance  varies 
directly  with  the  increase  in  velocity. 


22 


ROADS,  STREETS,  AND  PAVEMENTS. 


Some  of  M.  Morin’s  results  are  tabulated  below. 

- 1 

Relation  of  Force  of  Draught  to 
Weight  of  Vehicle  and  Load. 


Kind  of  Road. 

Carts. 

Trucks 
of  two 
tons. 

Diligences 
of  live  tons. 

Carriages 
with  seats 
hung  on 

springs. 

New  road,  with  gravel  cov- 

ering,  5 inches  thick. . . . 

tV 

i 

i 

i 

Solid  earth  causeway,  with 

gravel  covering  1J4  inch 

thick 

rs 

* 

To 

Earth  causeway  in  very 

good  condition 

tt 

T9 

YW 

t 

TT 

Walk. 

Trot. 

Walk. 

Trot. 

Broken  stone  road,  very 

dry  and  smooth. . 

TJ 

!>V 

T8 

4 h 

4T 

1 

TT 

Do.’  moist  and  dusty. . . 

i h 

T8 

TT 

YT 

34 

TT 

Do.  with  ruts  and  mud, 

sr 

^4 

A 

T8 

TT 

T9 

Do.  with  deep  ruts  and 

thick  mud 

tV 

TT 

* 

TI- 

T2 

TO 

(Dry 

To 

6T 

TT 

TS 

T9 

sV 

Pavement.  •< 

tV 

T3 

TT 

( Muddy 

T9 

TO 

_.1_ 

34 

The  smoother  the  road  and  the  less  rigid  the  vehicle,  the 
less  will  be  each  equal  increase  of  resistance  due  to  each 
equal  increase  of  speed. 

5.  The  traction  is  practically  independent  of  the  velocity 
upon  soft  dirt  and  sand  roads,  or  roads  freshly  and  thickly 
covered  with  gravel. 


GRADES  AND  TRACTIVE  FORCE, 


23 


6.  Upon  a smooth-cut,  evenly-laid  stone  pavement,  the 
resistance  at  a walking  speed  docs  not  exceed  three-fourths 
that  upon. the  best  Macadamized  road  at  the  same  speed,  but 
at  trotting  speed  it  is  equal  to  it. 

7.  The  wear  and  tear  of  the  road  is  greater  as  the  diam- 
eters of  the  wheels  are  less,  and  is  less  from  vehicles  with 
springs  than  from  those  without  them. 

The  following  table,  resulting  from  trials  made  with  a 
dynamometer  attached  to  a wagon  moving  at  a slow  pace 
upon  a level,  gives  the  force  of  traction  in  pounds  upon 
several  kinds  of  road-surfaces,  in  a fair  condition  ; the 
weight  of  wagon  and  load  being  one  ton  of  2,240  pounds. 


1.  On  best  stone  trackways 12}^  pounds. 

2.  A good  plank  road 82  to  50  pounds. 

8.  A cubical  block  pavement 32  to  38  “ 


4.  A Macadamized  road  of  small  broken  stones. ...  65  pounds. 

5.  A Telford  road,  made  with  six  inches  of  broken 

stone  of  great  hardness,  laid  on  a foundation 

of  large  stones  set  as  a pavement 46  pounds. 

6.  A road  covered  with  six  inches  of  broken  stone 

laid  on  concrete  foundation 46  “ 

7.  A road  made  with  a thick  coating  of  gravel  laid 

on  earth 140  to  147  pounda 

8.  A common  earth  road 200  pounds. 


In  order  to  apply  these  results  in  establishing  suitable 
grades,  take  the  case  of  the  Macadamized  road  No.  4,  in 
which  the  tractive  force  to  the  gross  ton  is  65  pounds  upon 
a level  road.  Let  W=  the  weight  of  the  vehicle  and  load 
in  pounds;  p—  pressure  normal  to  the  road-surface  in 
pounds ; t=force  of  traction  in  pounds  on  a level  road.  At 
the  angle  of  repose,  of  an  inclined  road,  the  force,  acting 
parallel  to  the  line  of  grade,  necessary  to  sustain  a carriage 


24 


ROADS,  STREETS,  AND  PAVEMENTS. 


and  its  load  in  its  position  on  the  incline,  or  to  prevent  it 
from  moving  hack  by  its  own  weight,  is  equal  to  the  traction 
force  t,  which  would  just  move  the  carriage  and  load  on 
a level  road.  Let  h be  the  perpendicular  and  b the  base  of 
a right  angle  triangle,  of  which  the  hypothenuse  B 0 (Fig.  5) 

represents  the  slope  of  the 
angle  of  repose,  which  some- 
what exceeds  the  greatest 
admissible  gradient.  For 
simplicity,  the  load  may  be 
supposed  to  rest  on  a single 
wheel,  shown  in  the  figure. 
In  the  smaller  similar  trian- 
gle t is  the  perpendicular, 
p the  base,  and  W the  hypothenuse,  in  which  p=  y^W2 t\ 


t h 


From  the  two  similar  triangles  t : p : : h : b,  or  ^ and 

t ^ h 

by  substitution  ^ ^ . But  being  the  perpen- 


dicular divided  by  the  base,  represents  the  angle  at  the  base, 
or  the  angle  of  repose,  and  this  is  the  maximum  admissible 
gradient.  Hence  the  gradient  should  not  exceed  the  quo- 
tient obtained  by  dividing  the  force  of  traction  by  the  square 
root  of  the  difference  between  the  square  of  the  load  and  the 
square  of  the  traction.  Upon  good  roads  t is  so  very  small 
in  proportion  to  W that  it  may  be  omitted  in  the  denomi- 
nator, and  we  have  practically  for  the  angle  of  repose  or 


the  force  of  traction  divided  by  the  weight  of  vehicle  and  load. 

65 

For  road  No.  4 the  formula  becomes  y'ohiO* — 65^*  = ^ 


GRADES. 


25 

nearly,  indicating  that  for  roads  upon  which  the  force 
of  traction  per  ton  is  65  pounds,  the  grade  should  be  not 
greater  than  1 perpendicular  to  34  base  ; and  generally  the 
proper  grade  for  any  kind  of  road,  or  the  ratio  of  the  verti- 
cal to  the  horizontal  line,  will  be  equal  to  the  ratio  between 
the  force  necessary  to  draw  the  load  and  the  load  itself, 
upon  the  same  road  when  level.  The  grade  is  usually  ex- 
pressed in  the  form  of  a vulgar  fraction,  having  1 for  the 
numerator,  and  the  horizontal  distance  corresponding  to  a 
rise  of  one  foot  for  the  denominator. 

In  practice  the  steepest  grades  that  can  be  allowed  upon 
Macadamized  or  Telford  roads,  in  the  condition  in  which 
their  road  surface  is  usually  maintained,  is  about  -fa,  it  hav- 
ing been  determined  by  experience  that  a horse  can  draw 
up  this  slope,  unless  it  be  a very  long  one,  his  ordinary  load 
for  a level  road,  without  the  help  of  a second  animal ; also 
that  he  can  attain  at  a walk,  a given  height,  upon  a gradient 
of  fa  without  more  apparent  fatigue,  and  in  nearly  the 
same  time  that  he  would  require  to  reach  the  same  height 
over  a proportionately  longer  road  with  a slope  so  gentle  — 
say  fa — that  he  could  ascend  it  at  a trot. 

It  is  however  more  desirable,  especially  for  passenger 
traffic,  to  keep  the  gradients  as  low  as  fa,  or  at  the  greatest 
fa,  as  the  maximum  slope,  whether  considered  as  an  ascent 
or  a descent , so  that  in  the  former  case  the  speed  need  not 
be  slower  than  a trot,  while  in  the  latter  it  will  not  be  neces- 
sary to  apply  a brake  to  prevent  the  load  pressing  forward 
upon  the  horses. 

Undulating  Grades. 

It  is  claimed,  as  having  been  demonstrated  by  experi- 
ence, that  a road  constructed  on  a dead  level,  or  with  a uni* 


26 


ROADS,  STREETS,  AND  PAVEMENTS. 


form  slope  between  points  upon  different  levels — especially 
if  the  slope  be  a long  one — is  somewhat  more  fatiguing  upon 
the  draft  of  the  horse  or  mule,  than  one  with  an  alterna- 
tion of  gentle  ascents  and  descents,  of  say  to  y^,  and 
that  a horse  can  draw  as  heavy  a load  at  as  great  a speed  up 
these  gradients,  if  they  are  of  moderate  length,  as  he  can 
upon  a perfect  level,  while  in  going  down  he  would  experi- 
ence a measure  of  relief,  hardly  perceptible  perhaps  at  the 
time,  but  which  during  several  days  of  continual  labor 
would  amount  to  a positive  benefit.  This  idea,  although  it 
has  the  appearance  of  great  plausibility,  is  probably  a mere 
popular  error,  unable  to  withstand  the  test  of  intelligent 
investigation.  Upon  a very  long  and  steep  gradient — one 
for  instance  greatly  exceeding  the  angle  of  repose,  and 
therefore  inadmissible  upon  good  roads — it  would  doubtless 
be  an  advantage  to  have  short  sections  upon  which  the  slope 
would  be  less  than  that  angle,  where  halts  could  be  made 
for  rest,  and  the  animals  be  entirely  relieved  of  pressure  in 
either  direction  ; but,  upon  a well  devised  road,  no  engineer 
would  be  justified  in  making  special  provisions  for  securing 
a succession  of  gentle  ascents  and  descents,  upon  any  consid- 
erations connected  solely  with  the  question  of  traction. 

The  proper  drainage  of  a road  requires  that  its  side 
ditches  should  have  a gentle  inclination  longitudinally, 
and,  in  order  that  the  road  surface  may  be  kept  free  from 
standing  water  without  giving  it  too  great  a rise  in  the  mid- 
dle, suitable  longitudinal  slopes  should  be  given  to  it.  For 
this  slope  English  engineers  generally  adopt  or  66  feet  to 
the  mile,  and  the  French  Corps  of  Ponts  et  Chaussees 
recommend  or  about  42  feet  to  the  mile. 


MAXIMUM  AND  MINIMUM  GRADES. 


Maximum  and  Minimum  Grades. 

As  a rule  therefore  the  gradients  or  longitudinal  slopes 
of  a road  should  be  established  between  1 in  30  and  1 in  125. 
It  is  generally  practicable  to  keep  within  the  maximum  of 

even  in  locating  a line  upon  a steep  hill-side,  by  giving 
it  a zigzag  direction,  connecting  the  straight  portions  by 
easy  curves. 

At  the  curves  the  gradients  should  be  somewhat  reduced, 
and  the  roadway  made  wider.  The  increase  in  width  should 
be  about  one-fourth,  when  the  angle  between  the  straight 
portions  is  from  120°  to  90°,  and  between  one-third  and  one- 
half  where  the  angle  is  from  90°  to  60°.  In  descending  a 
hill  there  is  a tendency  to  overturn  the  vehicle  at  the  curved 
portions,  from  the  effects  of  the  centrifugal  force,  and  this 
danger  is  in  proportion  to  the  speed  of  the  descent,  and  the 
sharpness  of  the  turn.  The  radius  of  the  curve  should 
therefore  be  great,  never,  if  practicable  less  than  100  feet. 
For  the  same  reason,  upon  all  sharp  curves,  the  road  sur- 
face should  not  be  the  highest  in  the  centre,  and  falling  in 
both  directions  so  as  to  drain  off  the  water,  but  should  be 
the  highest  on  the  outer  or  convex  side. 

In  long  ascents,  it  is  deemed  advantageous  to  make  the 
lowest  portion  comparatively  steep,  with  a corresponding 
reduction  in  the  gradient  near  the  summit,  in  order  that 
the  animals  may  achieve,  while  fresh,  as  much  of  the  rise  as 
possible,  while  the  more  gentle  slopes  are  left  for  the  last. 

Statical  Resistance  on  Grades. 

Returning  to  Fig.  5 (reproduced  in  Fig.  G),  let  us  sujv 


28 


ROADS,  STREETS,  AND  PAVEMENTS. 


pose  that  the  horizontal  A C is  of  such  length  that  the  ?er 
tical  rise  h=l  foot.  We  then  have 


Hence,  the  force  acting  parallel  to  an  inclined  road  neces- 


equal  to  the  weight  of  carriage  and  load  multiplied  by  the 
quotient  of  the  horizontal  length  divided  by  the  inclined 
length. 

For  example,  the  force  necessary  to  sustain  a carriage 
and  load  weighing  2500  pounds  upon  a road  with  a gradient 


These  results  are  theoretical.  They  approximate  to  prac- 
tical correctness,  as  the  friction  on  the  axles  is  diminished, 
and  the  smoothness  and  hardness  of  the  road  is  increased. 


W : BC: : t:  1, 
and  W:  BC  : : p:  AC, 
W 

from  which  we  get  t— 

13  0 


j 


Fig.  6. 


T 


sary  to  sustain  a carriage 
and  load  in  a state  of  rest,  is 
equal  to  the  weight  of  car- 
riage and  load  divided  by 
the  inclined  length  corre- 
sponding to  a rise  of  one 
foot.  And,  the  normal 
pressure  of  carriage  and  load 
upon  an  inclined  road  is 


2500 


of  1 in  20  is  ^ = 125  pounds  nearly,  and  the  normal 


20 


pressure  upon  the  road-surface  is  2500  X i — 2496. 

V 20  + 1 


DYNAMICAL  RESISTANCES. 


29 


Dynamical  Resistances.  Sir  John  Macniell’s 
Formulae. 

The  following  arbitrary  formulae  have  been  deduced  by 
Sir  John  Macniell  from  a number  of  experiments  upon  the 
several  descriptions  of  road  named  below,  with  stage-coaches 
and  wagons  moving  at  various  velocities,  and  carrying  vari- 
ous loads.  Enforce  required  to  move  the  vehicle;  W= 
weight  of  vehicle ; w= weight  of  load,  all  expressed  in 
pounds.  v=velocity  in  feet  per  second,  c is  a constant, 
depending  for  its  magnitude  upon  the  character  of  the  road- 
surface,  which,  for  the  several  roads  tried,  is  as  follows : 


On  a timber  surface,  or  on  a paved  road 

On  a well  made  broken  stone  road  in  a dry,  clean  state 

“ “ covered  with  dust 

“ “ “ wet  and  muddy 

On  a gravel  or  flint  road,  in  a dry,  clean  state 

“ “ wet  and  muddy 


For  a common  stage-wagon  the  formula  is. 


R= 


W -fw 
93 


wr 

+ 40+CT- 


c = 2 
c = 5 
c = 8 
c = 10 
c = 13 
c = 32 


and  for  a stage-coach, 


R— 


W -fw  w 


+ 77,+CV. 


100  40 

For  example,  the  force  necessary  to  move  a stage-coach 
weighing  2400  pounds,  loaded  with  2000  pounds,  &t  a speed 
of  six  feet  per  second,  upon  a level,  dry,  and  clean  gravel 


road,  is 


2400  + 2000  2000 


100 


+ 


40 


+ 6x13=:!  72  pounds. 


Mr.  Law’s  Table  of  Dynamical  Resistances. 

The  following  table,  prepared  by  curtailing  to  some  ex- 


30 


ROADS,  STREETS,  AND  PAVEMENTS. 


Kate  of  Inclination. 

1 

Angle  with  the  Horizon.  | 

For  a Stage-Wagon  and 

LOAD  OF  SIX  TONS,  MOVING 

AT  three  miles  per  hour. 

For  a Stage-Coach  and 

LOAD  OF  THREE  TONS,  MOV- 
ING AT  SIX  MILES  PER  HOUR. 

Force  required  to  draw  the 
wagon  up  the  incline. 

Force  required  to  draw  the 
wagon  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
wagon . 

Equivalent  length  of  level 
road  for  a descending 
wagon. 

Force  required  to  draw  the 
coach  up  the  incline. 

Force  required  to  draw  the 
coach  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
coach. 

Equivalent  length  of  level 
road  for  a descending 
coach. 

0 

' 

" 

lbs. 

lbs. 

Miles. 

Miles. 

lbs. 

lbs. 

Miles. 

Miles. 

1 in  260 

0 

13 

13 

315 

212 

1.196 

.8039 

387 

336 

1.071 

.9286 

“ 250 

0 

13 

45 

317 

210 

1.204 

.7963 

388 

335 

1.074 

.9259 

“ 240 

0 

14 

19 

320 

208 

1.212 

.7876 

890 

334 

1.077 

.9226 

“ 230 

0 

14 

57 

322 

205 

1.222 

.7785 

391 

332 

1.080 

.9192 

“ 220 

0 

15 

37 

325 

203 

1.232 

.7683 

392 

331 

1.084 

.9156 

“ 200 

0 

17 

11 

331 

197 

1,255 

.7451 

395 

328 

1.092 

.9071 

“ 180 

0 

19 

6 

338 

189 

1.283 

.7171 

399 

324 

1.103 

.8968 

“ 160 

0 

21 

29 

348 

180 

1.319 

.6814 

404 

320 

1.116 

.8839 

“ 140 

0 

24 

33 

360 

168 

1.364 

.6359 

410 

314 

1.132 

.8673 

“ 130 

0 

26 

27 

367 

160 

1.392 

.6079 

413 

310 

1.142 

.8573 

“ 120 

0 

28 

39 

376 

152 

1.425 

.5752 

418 

306 

1.154 

.8451 

" 110 

0 

31 

15 

386 

142 

1.451 

.5491 

423 

300 

1.169 

.8308 

“ 100 

0 

34 

23 

398 

129 

1.510 

.4903 

429 

294 

1.185 

.8142 

“ 95 

0 

36 

11 

405 

122 

1.537 

.4634 

432 

291 

1.195 

.8045 

“ 90 

0 

38 

12 

413 

114 

1.566 

.4338 

436 

287 

1.206 

.7937 

" 85 

0 

40 

27 

422 

106 

1.600 

.4004 

441 

282 

1.219 

.7801 

o 

00 

0 

42 

58 

432 

96 

1.637 

.3629 

446 

278 

1.232 

.7677 

“ 75 

0 

45 

51 

443 

85 

1.680 

.3204 

451 

272 

1.247 

.7522 

“ 70 

0 

49 

7 

456 

72 

1.728 

.2719 

457 

266 

1.265 

.7345 

“ 65 

0 

52 

54 

470 

57 

1.784 

.2161 

465 

258 

1.285 

.7143 

“ 60 

0 

57 

18 

488 

40 

1.850 

.1505 

474 

250 

1.309 

.6903 

“ 55 

1 

2 

30 

508 

19 

1.926 

.0736 

484 

239 

1.337 

.6620 

DYNAMICAL  RESISTANCES. 


31 


tent  a table  given  by  Mr.  Henry  Law,  0.  E.,  shows  with  an 
approximation  to  exactness,  quite  sufficient  to  make  it  very 
valuable,  the  force  required  to  draw  two  kinds  of  loaded 
vehicles,  one  weighing  with  its  load  6 tons  at  a speed  of  3 
miles,  and  the  other  weighing  with  its  load  3 tons  at  a speed 
of  6 miles  per  hour,  along  a Macadamized  road  in  its  usud 
state,  with  gradients  varying  from  1 in  7 to  1 in  600.  The 
table  also  gives  the  length  of  level  road  equivalent  to  1 mile 
of  the  inclined  road,  of  each  gradient,  “that  is  the  length 
which  would  require  the  same  mechanical  force  to  be  ex- 
pended in  drawing  a wagon  over  it,  as  would  be  necessary  tc 
draw  it  over  a mile  of  the  inclined  road.” 


Rate  of  Inclination. 

Angle  with  the  Horizon. 

Fora  Stage -Wagon  and 

LOAD  OF  SIX  TONS,  MOVING 
AT  THREE  MILES  PER  HOUR. 

For  a Stage-Coach  and 

LOAD  OF  THREE  TONS,  MOV- 
ING AT  SIX  MILES  PER  HOUR. 

Force  required  to  draw  the 
wagon  up  the  incline. 

Force  required  to  draw  the 
wagon  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
wagon. 

Equivalent  length  of  level 
road  for  a descending 
wagon. 

Force  required  to  draw  the 
coach  up  the  incline. 

Force  required  to  draw  the 
coach  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
coach. 

Equivalent  length  of  level 
road  for  a descending 
coach. 

o 

» 

lbs. 

lbs. 

Miles. 

Miles. 

lbs. 

lbs. 

Miles. 

Miles. 

1 in  600 

0 

5 

44 

286 

241 

1.085 

.9150 

373 

350 

1.030 

.9690 

“ 550 

0 

6 

15 

288 

239 

1.093 

.9074 

374 

349 

1.033 

.9662 

“ 500 

0 

6 

53 

291 

237 

1.102 

.8979 

375 

348 

1.037 

.9629 

“ 450 

0 

7 

38 

294 

234 

1.113 

.8869 

377 

347 

1.041 

.9588 

“ 400 

0 

8 

36 

297 

230 

1.128 

.8725 

378 

345 

1.046 

.9535 

“ 350 

0 

9 

49 

302 

225 

1.146 

.8543 

381 

342 

1.053 

.9469 

“ 300 

0 

11 

28 

309 

219 

1.170 

.8301 

384 

339 

1.061 

.9381 

“ 280 

0 

12 

17 

312 

216 

1.182 

.8179 

386 

338 

1.066 

.9336 

32 


ROADS,  STREETS,  AND  PAVEMENTS. 


Rate  of  Inclination. 

Angle  with  the  Horizon. 

For  a Stage-Wagon  and 

LOAD  OF  SIX  TONS,  MOVING 
AT  THREE  MILES  PER  HOUR. 

For  a Stage-Coach  and 

LOAD  OF  THREE  TONS,  MOV- 
ING AT  SIX  MILES  PER  HOUR. 

Force  required  to  draw  the 
wagon  up  the  incline. 

Force  required  to  draw  the 
wagon  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
wagon. 

Equivalent  length  of  level 
road  for  a descending 
wagon. 

Force  required  to  draw  the 
coach  up  the  incline. 

Force  required  to  draw  the 
coach  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
coach. 

Equivalent  length  of  level 
road  for  a descending 
coach. 

o 

/ 

// 

lbs. 

lbs. 

Miles. 

Miles. 

lbs. 

lbs. 

Miles. 

Miles. 

1 in  50 

1 

8 

6 

533 

2.019 

.... 

496 

227 

1.371 

.6283 

“ 45 

1 

16 

24 

562 

2.133 

511 

212 

1.412 

.5871 

“ 40 

1 

25 

57 

600 

2.274 

530 

194 

1.464 

.5354 

“ 35 

1 

38 

14 

648 

2.456 

554 

170 

1.530 

.4690 

“ 34 

1 

41 

8 

659 

2.499 

559 

164 

1.546 

.4535 

“ 33 

1 

44 

12 

671 

2.544 

565 

158 

1.562 

.4370 

“ 32 

1 

47 

27 

684 

2.593 

572 

152 

1.580 

.4193 

“ 31 

1 

50 

55 

697 

2.644 

578 

145 

1.599 

.4007 

“ 30 

1 

54 

37 

712 

.... 

2.699 

586 

138 

1.619 

.3805 

“ 29 

1 

58 

34 

727 

2.756 

593 

130 

1.640 

.3592 

4 4 28 

2 

2 

5 

744 

2.820 

602 

122 

1.663 

.3363 

“ 27 

2 

7 

2 

762 

2.888 

610 

113 

1.688 

.3119 

“ 26 

2 

12 

2 

781 

2.960 

620 

103 

1.714 

.2854 

“ 25 

2 

17 

26 

801 

3.038 

630 

93 

1.743 

.2566 

“ 24 

2 

23 

10 

823 

3.120 

641 

82 

1.774 

.2257 

“ 23 

2 

29 

22 

847 

3.213 

653 

69 

1.808 

.1919 

22 

2 

36 

10 

874 

3.313 

666 

56 

1.844 

.1554 

“ 21 

2 

43 

35 

903 

3.423 

681 

42 

1.884 

.1150 

“ 20 

2 

51 

21 

933 

3.538 

696 

26 

1.926 

.0730 

‘4  19 

3 

0 

46 

970 

.... 

3.677 

714 

8 

1.977 

.0221 

“ 18 

3 

10 

47 

1009 

— 

3.826 

734 

— 

2.082 

.... 

17 

3 

21 

59 

1053 

3.991 

756 

.... 

2.092 

.... 

DYNAMICAL  RESISTANCES, 


33 


Rate  of  Inclination. 

Angle  with  the  Horizon. 

For  a Stage-Wagon  and 

LOAD  OF  SIX  TONS,  MOVING 
AT  THREE  MILES  PER  HOUR. 

For  a Stage-Coach  and 

LOAD  OF  THREE  TONS,  MOV- 
ING AT  SIX  MILES  PER  HOUR. 

Force  required  to  draw  the 
wagon  up  the  incline. 

I Force  required  to  draw  the 
| wagon  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
wagon. 

Equivalent  length  of  level 
road  for  a descending 
wagon. 

Force  required  to  draw  the 
coach  up  the  incline. 

Force  required  to  draw  the 
coach  down  the  incline. 

Equivalent  length  of  level 
road  for  an  ascending 
coach. 

Equivalent  length  of  level 
road  for  a descending 
coach. 

o 

t 

" 

lbs. 

lbs. 

Miles. 

Miles. 

lbs. 

lbs. 

Miles. 

Miles. 

lin  16 

3 

34 

35 

1102 

4.178 

780 

2.160 

“ 15 

3 

48 

51 

1157 

4.388 

807 

2.234 

“ 14 

4 

5 

14 

1221 

4.629 

839 

2,322 

“ 13 

4 

23 

56 

1294 

4.906 

875 

2.423 

“ 12 

4 

45 

49 

1379 

5.229 

.... 

918 

2.540 

“ 11 

5 

11 

40 

1480 

5.611 

.... 

968 

2.679 

“ 10 

5 

42 

58 

1600 

6.067 

1028 

2.846 

“ 9 

6 

20 

25 

1747 

6.623 

— 

1101 

3.048 

“ 8 

7 

7 

30 

1929 

7.315 

— 

1192 

3.300 

“ 7 

8 

7 

48 

2162 

8.199 

.... 

1308 

3.621 

.... 

From  the  foregoing  table  we  see  : 

1.  That  the  force  necessary  to  move  a vehicle  at  a certain 
velocity  on  a level  road  must  be  decreased  on  a descending 
grade  to  precisely  the  same  extent  that  it  must  be  increased 
in  ascending  the  same  grade,  in  order  to  maintain  the  same 
velocity. 

2.  It  must  not,  however,  be  inferred  from  this  that  the 
animal  force  expended  in  passing  and  repassing  on  the  same 
road,  will  gain  as  much  in  descending  the  several  grades  as 
it  will  lose  in  ascending  them.  The  animal  force  must  be 


34 


ROADS,  STREETS,  AND  PAVEMENTS. 


adequate,  either  in  number  or  in  power,  for  achieving  the 
steepest  ascending  grades  on  any  route,  and  no  reduction  in 
the  number  of  animals  will  be  practicable  in  the  general  case, 
in  descending  that  or  the  lower  grades,  or  upon  the  level 
portions  of  the  line. 


CHAPTER  II. 


EARTHWORK,  DRAINAGE  AND  TRANSVERSE  FORM  OF 
COUNTRY  ROADS. 

Excavations  and  Embankments. 

Due  regard  to  economy  in  the  cost  of  constructing  a road 
generally  requires  that  its  location  shall  be  such  that  the 
cuttings  shall  balance  the  fillings,  or  in  other  words  that  the 
excavations,  at  points  where  the  ground  is  higher  than  the 
road,  shall  furnish  the  contiguous  embankments  at  points 
where  the  road  is  higher  than  the  natural  surface.  Such, 
however,  is  not  always  the  case,  it  being  cheaper,  under  some 
circumstances,  to  deposit  the  excavations  in  spoilbanks , and 
procure  the  earth  for  embankment  from  side-cuttings  near  by. 

The  first  location  of  the  road  upon  the  map  will  seldom 
be  more  than  an  approximation  to  the  best  line,  which  must 
finally  be  ascertained  after  successive  approximations,  for 
each  of  which  a series  of  new  sections  must  be  drawn,  and 
new  calculations  made.  The  contour  lines  referred  to,  of 
which  an  example  is  given  in  Fig.  3,  or  the  parallel  cross- 
sections  as  shown  in  Fig.  4,  will  be  of  great  assistance  in 
making  these  computations,  and  will  materially  abridge  the 
labor  of  locating  the  line. 

The  “ Lead.” 

Prof.  Mahan  says,  “In  the  calculations  of  the  solid 
contents  required  in  balancing  the  excavations  and  embank- 
ments the  most  accurate  method  consists  in  subdividing  the 


36 


ROADS,  STREETS,  AND  PAVEMENTS. 


different  solids  into  others  of  the  most  simple  geometrical 
forms  as  prisms,  prismoids,  wedges  and  pyramids,  whose 
solidities  are  readily  determined  by  the  ordinary  rules  for 
the  mensuration  of  solids.”  Other  methods  “consist  in 
taking  a number  of  equidistant  profiles,  and  calculating  the 
solid  contents  between  each  pair,  either  by  multiplying  the 
half  sum  of  their  areas  by  the  distance  between  them,  or  by 
taking  the  profile  at  the  middle  point  between  each  pair,  and 
multiplying  its  area  by  the  same  length  as  before.”  In  order 
to  save  labor  and  insure  accuracy,  tables  for  these  calcula- 
tions have  been  prepared  and  published. 

Care  must  be  taken  in  determining  the  lead , or  the  aver- 
age distance  to  which  the  cuttings  must  be  transported  in 
making  the  fillings,  a distance  usually  assumed,  in  each  case, 
to  be  the  length  of  the  right  line  joining  the  centre  of  grav- 
ity of  the  solid  of  excavation  and  that  of  embankment.  The 
least  possible  lead  is  essential  from  considerations  of  econ- 
omy, and  this  is  usually  secured  when  such  conditions  are 
interposed  that  the  paths  over  which  the  different  portions 
of  the  solid  of  excavation  are  conveyed  away  to  the  solid  of 
embankment,  shall  not  cross  each  other  either  horizontally  or 
vertically. 

These  conditions  require  that  the  sum  of  the  products, 
obtained  by  multiplying  all  the  elementary  volumes  by  the 
distances  over  which  they  are  respectively  transported,  shall 
be  a minimum.  As  the  computations  involve  the  employ- 
ment of  the  higher  mathematics,  they  are  not  inserted 
here. 

Growth  of  Excavated  Earth. 

It  must  be  remembered  that  the  different  kinds  of  earth 
Jo  not  fill  the  same  volume  in  artificial  embankments  that 


MOVING  EARTH. 


37 


they  previously  occupied  in  their  natural  bed.  The  growth , 
or  augmentation  in  volume,  of  freshly-dug  earth,  varies  from 
15  to  25  per  cent  among  the  various  kinds,  but  where  formed 
and  compacted  into  embankments,  it  settles  or  shrinks  to 
less  than  its  bulk  in  the  natural  bed.  This  shrinking  for 
different  earths,  is  approximately  as  follows  : gravel  or  sand 
about  8 per  cent ; clay  about  10  per  cent ; loam  about  12 
per  cent ; loose  vegetable  surface  soil  about  15  per  cent ; 
puddled  clay  about  25  per  cent.  Mr.  John  0.  Trautwine, 
C.  E.,  found  that  1 cubic  yard  of  hard  rock  broken  into  frag- 
ments made  1 T\-  cubic  yards  of  loose  heap  ; If  cubic  yards 
carelessly  piled ; 1T%  cubic  yards  carefully  piled ; l-J  cubic 
yards  of  very  carelessly  scabbled  rubble,  or  1£  cubic  yards  of 
somewhat  carefully  scabbled  rubble. 

Moving  Earth. 

In  excavating  and  removing  earth,  it  is  first  loosened 
with  picks,  spades  or  plows,  and  then  shoveled  into  the 
barrows  or  carts  which  convey  it  away.  For  short  haulages, 
say  of  90  to  100  feet,  the  ordinary  road-scraper  holding  about 
A<*f  a cubic  yard  may  be  advantageously  used,  when  the 
height  to  which  the  earth  has  to  be  raised  does  not  necessi- 
tate ascents  steeper  than  1 in  5.  For  distances  exceeding 
the  sphere  of  scrapers,  or  where  these  cannot  be  advantage- 
ously employed,  earth  is  generally  conveyed  in  wheel-bar- 
rows. The  limiting  distance,  when  one-horse  carts  should 
replace  barrows,  will  seldom  exceed  250  feet  for  all  the  various 
kinds  of  earth.  This  includes  loosening,  loading,  moving, 
spreading,  and  the  wear  and  tear  of  vehicles  and  tools.  It  is 
stated  that,  upon  English  works,  with  barrows  holding  ^ of 
*i  cubic  yard,  the  limit  is  300  feet. 


One-horse  Carts.  Wheelbarrows.  I Kind  of  Vehicle. 


38 


ROADS,  STREETS,  AND  PAVEMENTS. 


| Length  of  lead,  or  dis- 
tance MOVED  IN  FEET. 

Number  of  cubic  yards 
in  place,  moved  per 

DAY  BY  EACH  VEHICLE. 

Pure,  stiff 
Clay,  or 

CEMENTED 

Gravel. 

Light,  sandy 
Soils. 

Strong,  heavy 
Soils. 

Loosened 
with  pick. 

Loosened 
with  plow. 

Loosened 
with  pick. 

Loosened 
with  plow. 

Loosened 
with  pick. 

Loosened 
with  plow. 

cents. 

cents. 

cents. 

cents. 

cents. 

cents. 

('  25 

25.7 

14.62 

10.12 

8.79 

7.52 

11.62 

9.12 

50 

22.1 

15.30 

10.80 

9.47 

8.20 

12.30 

9.80 

75 

19.3 

16.02 

11.52 

10.19 

8.92 

13.02 

10.52 

100 

17.1 

16.74 

12.24 

10.91 

9.64 

13.74 

11.24 

150 

14.0 

18.15 

13.65 

12.32 

11.05 

15.15 

12.65 

200 

11.9 

19.52 

15.02 

13.69 

12.42 

16.52 

14.02 

250 

10.3 

20.95 

16.45 

15.12 

13.85 

17.95 

15.45 

300 

9.07 

22.40 

17.90 

16.57 

15.30 

19.40 

16.90 

400 

7.36 

25.20 

20.70 

19.37 

18.10 

! 

22.20 

19.70 

300 

28.6 

20.98 

15.48 

13.50 

12.23 

17.98 

15.48 

400 

25.0 

21.71 

17.21 

14.23 

12.46 

18.71 

16.21 

500 

22.2 

22.44 

17.94 

14.96 

13.69 

19.44 

16.94 

700 

18.2 

23.88 

19.38 

16.40 

15.13 

20.88 

18.38 

1000 

14.3 

26.05 

21.55 

18.57 

17.30 

23.05 

20.55 

1400 

11.1 

28.91 

24.41 

21.43 

20.16 

25.91 

23.41 

2000 

8.33 

33.31 

28.81 

25.83 

24.56 

30.31 

27.81 

Yz  mile 

6.58 

37.95 

33.45 

30.47 

29.20 

34.95 

32.45 

3000 

5.88 

40.51 

36.01 

33.03 

31.76 

37.51 

35.01 

3500 

5.13 

44.11 

39.61 

36.63 

35.36 

41.11 

36.61 

4000 

4.54 

47.81 

43.31 

40.33 

39.06 

44.81 

42.31 

1 mile 

3.52 

57.09 

52.59 

49.61 

48.34 

54.09 

51.59 

1 Yt  mile 

2.40 

76.33 

71.83 

68.85 

67.58 

73.33 

70  83 

MAP  AND  SPECIFICATIONS. 


39 


Beyond  a certain  distance  two-horse  wagons  should  take 
the  place  of  carts  ; and  where  the  lead  is  to  1|  miles  a tem- 
porary railway  and  a locomotive  engine  and  dirt-cars  become 
desirable.  Within  the  last  few  years  steam  excavators,  capa- 
ble of  digging  and  loading  100  cubic  yards  per  hour,  at  a 
cost  of  2i  to  3 cents  per  yard,  have  been  used  upon  some 
extensive  works. 

The  cost  per  cubic  yard  of  loosening,  loading,  trans- 
porting to  different  distances,  and  spreading  soils,  includ- 
ing repairs  to  vehicles  and  tools,  is  given  in  the  foregoing 
table  (condensed  from  Trautwine),  based  on  man’s  labor  at 
$1.00,  horse  at  75  cents,  and  cart  at  25  cents  per  day;  one 
driver  to  4 carts. 

Completed  Map,  and  Specifications. 

Having  finally  adjusted  all  questions  of  gradients,  exca- 
vations and  embankments,  and  re-examined  the  ground,  the 
line  adopted  should  be  carefully  plotted  upon  the  map, 
together  with  longitudinal  and  numerous  cross-sections,  to 
show  the  cuttings  and  fillings,  as  well  as  the  natural  surface 
of  the  ground. 

Specifications  of  the  several  kinds  of  work,  and  working 
drawings  of  bridges,  culverts,  etc.,  should  also  be  prepared. 

Upon  the  longitudinal  section  of  the  road,  at  points 
taken  at  equal  intervals  apart  (say  50,  75  or  100  feet)  the 
vertical  distance  of  the  natural  surface  above  or  below  the 
road  surface  should  be  marked  in  feet  and  inches. 

In  order  to  indicate  the  grades,  the  heights  of  the  same 
points  above  an  assumed  horizontal  line  called  the  datum 
line , should  also  be  marked.  These  points  should  be  num- 
bered on  the  drawing. 


40 


ROADS,  STREETS,  AND  PAVEMENTS. 


Fixing  the  Line  on  the  Ground. 

The  axis  of  the  road  is  located  on  the  ground  by  driving 
Btakes  to  correspond  with  the  several  points  on  the  map. 
These  stakes  are  lettered  cut , or  fill,  with  the  number  of  feet 
added,  to  indicate  that  the  natural  surface  at  these  points 
must  be  cut  down  or  filled  up  the  specified  distance,  in  order 
to  attain  the  position  of  the  road  surface.  Stakes  showing 
the  width  of  the  roadway,  and  the  lateral  limits  of  the  cut- 
tings and  fillings  should  also  be  established. 

Earthwork  is  a term  applied  to  the  movement  and  dis- 
posal of  earth,  whether  the  material  handled  be  common 
earth  or  rock. 

Side  Slopes  in  Cuttings. 

In  excavations , the  inclination  which  should  be  given  to 
the  side  slopes,  and  the  measures,  if  any,  which  should  be 
adopted  for  giving  stability  to  their  surfaces,  will  be  gov- 
erned in  a great  measure  by  the  inclination  and  direction  of 
the  strata,  the  kind  of  soil,  the  degree  of  exposure  to  the 
action  of  springs,  and  the  severity  of  the  seasons. 

On  most  soils,  such  as  garden  loam,  and  other  mixtures 
of  clay  and  sand,  compact  clay,  and  compact  stony  or  grav- 
elly soils,  the  slopes  should  be  about  two  base  to  one  (or  at 
most  one  and  a half,)  perpendicular.  In  some  cases  an 
angle  of  45°,  or  1 on  1,  will  answer. 

It  is  always  desirable  that  the  roadway  should  be  exposed 
as  fully  as  possible  to  the  action  of  the  wind  and  sun,  in 
order  to  facilitate  the  evaporation  of  moisture  from  its  sur- 
face. Hence,  the  deeper  the  excavation,  the  more  gentle 
should  be  the  side  slopes,  particularly  those  on  the  south 
side  in  high  northern  latitudes.  When  the  slopes  are 


SIDE  SLOPES  IK  CUTTIKGS. 


41 


exposed  to  no  other  causes  of  destruction  than  the  action  of 
the  elements — to  wind,  rain,  and  frost — it  is  not  essentia] 
(hat  any  special  precautions  should  be  adopted  for  their 
protection,  although  the  expense  of  maintenance  will  be 
considerably  lessened  by  sodding  them,  or  by  first  covering 
them  with  three  or  four  inches  of  rich  soil  and  then  seeding 
them  down,  or  setting  them  with  plants  of  some  suitable 
variety  of  grass. 

If  the  soil  be  infested  with  springs  that  might  destroy 
the  stability  of  the  slopes,  and  wash  them  down  into  the 
roadway,  they  should  if  practicable  be  tapped  near  their 
source  by  digging  into  the  side  of  the  slope,  and  the 
water  conveyed  by  blind  drains  or  otherwise  into  the  side 
drains.  After  the  drain  is  constructed  the  earth  is  filled 
in  over  it,  and  the  slope  restored  to  the  required  shape. 
Figs.  7,  8 and  9 show  cross  sections  of  three  forms  of  drains, 


Fig.  7.  Fig.  8.  Fig.  9. 


either  of  which  will  answer  for  this  purpose,  in  ordinary 
cases.  Fig.  7 is  constructed  with  three  fascines,  laid  lon- 
gitudinally in  the  trench  excavated  to  the  source  of  the 
spring.  A single  fascine  of  equivalent  area  in  cross-section, 
or  loose  brushwood  placed  compactly  in  the  trench,  may  be 
substituted.  Fig.  8 shows  a blind  drain  of  fragments  of 
stone  or  loose  rubble.  In  Fig.  9 a clear  water  way  is  left 
.n  the  middle  of  the  drain.  In  either  case  the  sides  and  top 


42 


ROADS,  STREETS,  AHD  PAVEMEHTS. 


of  the  drain  should  be  covered  with  straw,  coarse  gra£3, 
small  brushwood,  or  sods  with  the  grass  side  next  the  drain, 
to  prevent  the  latter  becoming  choked  with  earth. 

In  cases  where  the  entire  body  of  the  slope  is  saturated 
with  water,  and  the  sources  of  the  springs  are  unknown,  or 
cannot  be  reached,  good  drainage  may  generally  be  secured 
by  a series  of  blind  drains  extending  a few  feet  into  the 
slope  at  its  base,  or  by  a single  drain  constructed  of  loose 
stone  in  the  form  of  an  inclined  retaining  wall,  parallel 
with  the  foot  of  the  slope,  as  shown  in  Fig.  10.  Similai 


precautions  to  those  already  mentioned  must  be  taken  in 
this  case  to  prevent  the  drain  becoming  choked.  A series 
of  parallel  tile  drains  in  the  body  of  the  slope,  six  to  eight 
feet  apart,  and  four  to  six  feet  below  the  surface,  will  some- 
times secure  good  drainage  in  springy  soils.  The  round 
tiles  are  the  best,  and  the  diameter  of  the  bore  need  not 
exceed  one  to  two  inches.  They  are  laid  end  to  end  in  a 
narrow  trench,  then  covered  with  straw,  hay,  or  turf  to  pre- 
vent their  choking,  and  the  trench  filled  up.  These  drains 
should  have  an  inclination  of  one  in  eighty  to  one  in  one 
hundred,  and  may  all  empty  into  a masonry  conduit  or 
earthen  pipe  leading  dowm  the  slope  into  the  side  drains  of 
the  roadway.  Instances  may  occur  where  a deep  narrow 
trench  dug  just  beyond  the  crest  of  the  side  slope,  and  filled 


SIDE  SLOPES  IK  CUTTIKGS. 


43 


up  with  broken  stone  or  pebbles,  will  cut  off  all  the  springs. 
As  such  an  arrangement  will  also  prevent  the  surface  water 
from  higher  levels  from  running  over  the  slope,  it  may  be 
the  least  costly  method  of  effecting  good  drainage.  Deep 
shafts  for  collecting  the  water  are  sometimes  sunk  from  the 
natural  surface  above  the  crest  of  the  slope,  and  the  water 
conveyed  from  them  into  the  side  drains  of  the  roadway, 
through  pipes  or  drains  laid  by  tunneling.  In  deep  cut- 
tings in  clayey  soils,  of  such  character  that  water  will 
render  them  sufficiently  plastic  to  slide  down  the  slope,  or 
soils  easily  cut  into  gullies  by  running  water,  it  is  well  to 
form  the  slope  in  benches  or  berms,  shaped  into  shallow 
drains  called  catchwater  drains,  to  receive  the  water  and 
earth  from  the  higher  levels.  They  should  have  a slight  in- 
clination longitudinally,  so  as  to  discharge  their  water  at 
the  foot  of  the  slope,  or,  at  suitable  intervals,  into  paved 
open  drains  running  directly  down  the  face  of  the  slope. 

In  soils  formed  in  great  part  of  unctuous  clay,  or  alternate 
layers  of  clay  and  sand,  there  is  always  a tendency  to  slides 
during  the  wet  season,  or  during  the  spring  in  high  latitudes, 
when  the  frost  is  leaving  the  ground.  Under  these  circum- 
stances special  precautions  should  be  taken  for  the  protection 
of  the  side  slopes,  such  as  (1)  cutting  off  all  springs  if  any 
exist,  (2)  turning  off  the  water  from  the  higher  levels  by  a 
drain  above  the  crest  of  the  slope,  and  (3)  arrangements 
for  conveying  off  the  water  which  falls  upon  the  slopes, 
either  by  carefully  constructed  catchwater  drains,  by  sod- 
ding the  slope,  or  by  a combination  of  the  two.  Before  top- 
dressing the  slope  with  rich  soil,  preparatory  to  sodding  oi 

seeding  down,  it  should  be  cut  into  horizontal  benches  oi 

» 

steps  to  guard  against  slides,  as  shown  on  the  right  in  Fig. 
10.  This  method  may  be  advantageously  applied  to  those 


44 


ROADS,  STREETS,  AtfD  DAVEMEKTS. 


kinds  of  slaty  rocks  which  disintegrate  rapidly  by  alternate 
freezing  and  thawing.  (The  benches  are  incorrectly  repre- 
sented on  the  left  hand  slope  in  the  figure.) 

Although  the  sides  of  a cutting  through  compact  rock 
would  stand  firmly,  if  left  in  a vertical  position,  it  is  desira- 
ble that  they  should  be  sloped  to  some  extent  so  as  to  expose 
the  road-surface  to  the  drying  influences  of  the  wind  and  sun. 
Unless  prevented  by  considerations  of  economy,  the  slope 
on  the  side  next  the  equator  in  high  latitudes,  should  be  as 
great  as  one  base  to  one  perpendicular,  while  one  base  to  twe 
perpendiculars  will  ordinarily  answer  on  the  opposite  side. 

When  the  depth  of  the  excavation  exceeds  a certain 
limit,  generally  assumed  to  be  about  60  feet,  it  is  in  most 
cases  cheaper  to  tunnel  than  to  make  a cut.  It  is  however, 
seldom  necessary  to  resort  to  this  expedient,  in  constructing 
common  roads,  for  which  indeed  it  is  peculiarly  inappropri- 
ate, on  account  of  excluding  the  wind  and  sun. 

Embankments . 

Embankments  should  be  made  sufficiently  firm  and  com- 
pact to  resist  all  tendency  to  unequal  settlement  and  slides. 
They  should  therefore  possess  not  only  great  but  uniform 
solidity,  especially  if  they  are  high,  conditions  which  are 
best  secured  by  forming  them  in  successive  horizontal  layers 
well  compacted  by  ramming.  As  this  method  is  expensive, 
it  is  usual,  from  considerations  of  economy,  to  carry  out  an 
embankment  to  its  full  height  from  the  beginning,  at  the 
same  time  making  the  cut,  which  supplies  the  earth,  to  its 
full  depth.  The  earth,  on  being  tipped  at  the  end  of  the 
bank  undergoing  formation,  slides  down  the  slope  and  finally 
comes  to  temporary  rest,  approximately  at  the  angle  ol 
repose.  (See  Fig.  11). 


EMBANKMENTS. 


45 


As  the  rapidity  with  which  this  kind  of  work  can  be 
executed  depends  upon  the  number  of  “tipping  places” 


afforded  by  the  width  of  the  embankment,  it  is  usual  to  form 
the  latter  at  first  broader  at  the  top,  and  correspondingly 
narrower  at  the  bottom  than  the  required  dimensions,  main- 
taining of  course  the  requisite  area  of  cross-section.  The 
excess  at  the  top  (the  angles  at  A and  0,  Fig.  12)  is  after- 


wards moved  down  to  the  bottom,  thus  securing  the  required 
width  of  base,  and  inclination  of  side  slopes. 

The  sides  of  the  embankment  should  always  be  kept 
somewhat  higher  than  the  centre  line,  in  order  to  retain  the 
rain  fall,  and  consequently  hasten  the  consolidation  of  the 
mass.  For  the  same  reason  when  the  case  will  warrant  the 
expense  of  constructing  in  successive  horizontal  layers  they 


snou Id  be  made  concave  on  the  top,  as  shown  in  Fig.  13 
This  will  also  lessen  the  danger  of  slides. 


4(5 


ROADS,  STREETS,  AND  PAVEMENTS. 


Embankment  Slopes. 

The  foot  of  the  slope  may  be  secured  by  resting  it  in  a 
shallow  trench,  or  by  abutting  it  against  a low  dry  wall  of 
stone  (Fig.  13),  and,  in  localities  where  there  is  an  abun- 
dance of  stone  to  be  obtained  in  the  proper  shape  at  moder- 
ate cost:,  the  entire  slope  may  sometimes  be  advantageously 
replaced  by  a sustaining  wall  laid  up  without  mortar.  In 
cases  where  the  embankments  require  more  earth  than  the 
necessary  excavations  afford,  a sustaining  wall  may  be  cheaper 
even  in  its  first  cost,  than  a slope  of  earth,  while  the  current 
cost  of  its  maintenance  will  be  small  in  comparison  with 
that  of  earthwork. 

The  inclination  of  the  slopes  should  be  less  than  the  earth 
will  naturally  assume,  in  order  to  give  them  greater  stabil- 
ity, and  they  should  be  protected  by  sodding  or  seeding  down. 

The.  surface  water  of  the  top  may  be  collected  by  side- 
drains  and  carried  down  the  slopes  at  intervals  either  in 
paved  gutters  or  blind  drains.  If  allowed  to  shed  itself 
over  the  slope,  gullies  would  be  formed,  and  the  embank- 
ment eventually  destroyed. 

When  extensive  excavations  have  to  be  made  through 
rock,  and  stone  for  embankment  purposes  is  therefore  plenty 
and  cheap,  the  entire  face  of  the  slope  may  be  roughly  paved 
or  covered  with  stone,  at  moderate  cost,  rendering  all  other 
precautions  for  its  preservation  unnecessary.  Fragments  of 
various  sizes  and  shapes,  from  one  to  two  feet  in  length,  may 
be  used  for  this  purpose.  They  should  be  placed  generally 
with  the  longest  edges  down,  their  faces  at  right  angles  to 
the  slope  and  parallel  with  the  axis  of  the  road.  It  is  not 
usual  to  protect  the  slopes  of  embankments  in  this  careful 


HILL-SIDE  ROADS. 


47 


manner,  but  they  should  never  be  required  to  carry  off  the 
surface  water  of  the  roadway. 

Hill-Side  Roads. 

A roadway  located  upon  a hill-side  is  usually  formed  half 
in  excavation,  and  half  in  embankment,  allowance  being 
made  for  the  shrinkage  of  the  latter.  To  guard  against 
slides,  the  natural  surface  should  be  prepared  to  receive  the 
embankment,  by  cutting  it  into  benches  as  in  Fig.  14.  The 


foot  of  the  slope  should  abut  against  a low  dry  stone  wall 
below  the  reach  of  frost.  At  the  crest  of  the  slope  in  exca- 
vation, an  open  trench  should  be  formed  to  intercept  and 
convey  away  the  surface  water  from  the  higher  ground. 

Upon  steep  hill-sides,  the  side  slopes  of  excavation  and 
of  embankment  must  both  be  replaced  by  sustaining  walls. 
Dry  walls  will  usually  answer  for  these  purposes,  if  the  stone 
can  be  procured  of  suitable  sizes.  (Fig.  15.) 

If  the  hill-side  upon  which  the  road  is  located  be  a rocky 
ledge  of  less  inclination  than  one  perpendicular  to  one  base, 
the  same  method  of  construction  by  making  the  excavations 
Bupply  the  embankments  may  be  followed.  The  enrockment 


ROADS,  STREETS,  ANU  PAVEMEHTS. 


48 

filling  in  this  case  will  occupy  a greater  volume  than  the  cut- 
ting from  which  it  is  taken. 


example  when  it  is  steeper  than  one  base  to  one  and  a half 
perpendicular,  the  whole  roadway  may  be  formed  in  excava- 
tion, or,  as  shown  in  Fig.  16,  by  cutting  the  face  of  the  ledge 
into  two  or  more  horizontal  steps  with  vertical  faces,  and 
building  up  the  embankment  in  the  form  of  a solid  stone  wall, 
in  horizontal  courses,  either  with  or  without  mortar.  In  the 
figure  the  lower  step,  on  which  the  wall  rests,  may  sometimes 
be  advantageously  replaced  by  two  smaller  steps,  a , c,  and 
b , b.  On  account  of  the  great  comparative  cost  of  excava- 
tions in  ropk,  estimates  for  work  of  this  character  should 
always  be  based  upon  numerous  and  careful  sections.  All 
attempts  to  lessen  the  quantity  of  excavation  by  increasing 
the  number  and  diminishing  the  width  of  the  steps,  require 
additional  precautions  against  settlement  in  the  built-up 
portion  of  the  roadway. 


ROADS  ON  MARSHY  GROUND. 


49 


Roads  over  Marshes  and  Swamps. 

If  the  road  runs  through  a swamp  or  marsh  resting  upon 
a firm  substratum,  the  soft  material  should  be  removed 
when  its  depth  does  not  exceed  two  or  three  feet,  and  the 
road  embankment  formed  directly  upon  the  hard  soil.  A 
wide  and  deep  open  ditch  should  be  cut  in  the  marsh  on 
each  side  of  the  road,  to  receive  the  surface  drainage  and  cut 
off  the  water  from  the  adjacent  marsh. 

Roads  over  deep  marshes  must  be  constructed  upon  a 
different  plan.  A system  of  thorough  deep  drainage  being 
essential,  the  method  usually  followed  is  to  cut  a deep  and 
wide  ditch  on  each  side,  leaving  between  each  ditch  and  the 
road  covering  an  unoccupied  strip  or  berm  several  feet  in 
width.  Cross  drains  should  connect  the  two  main  drains  at 
frequent  intervals,  to  drain  the  soil  under  the  roadway. 
These  cross  drains  are  formed  by  digging  trenches  a little 


50 


HOADS,  STREETS,  AND  PAVEMENTS. 


deeper  than  the  lowest  water  level  in  the  side  ditches,  and 
filling  them  with  fragments  of  stone.  If  water  permanently 
stands  in  the  main  drains,  the  cross  drains  may  be  filled 
below  the  water  level  with  brushwood  or  fascines.  On  the 
foundation  thus  formed  the  roadway  may  be  constructed. 

In  deep  marshy  soils  having  a spongy  subsoil,  it  is  some- 
times necessary  to  form  an  artificial  bed  for  the  road  cover- 
ing. In  some  cases  of  rather  firm  marsh,  it  is  sufficient  to 
remove  the  soft  top-soil  to  a depth  of  three  or  four  feet,  and 
substitute  for  it  sand,  gravel,  or  other  compact  material  that 
will  not  retain  water.  Upon  this  bed  the  road  covering  is 
placed.  In  others  a bed  formed  of  fascines  has  been  used 
with  success.  Fascines  are  made  by  binding  together,  by 
wires  or  withes,  in  cylindrical  bundles  nine  to  ten  inches  in 
diameter  and  ten  to  twenty  feet  long,  slender  branches  of 
underwood.  A layer  of  fascines,  placed  across  the  road, 
side  by  side,  is  first  laid  down.  A second  layer  at  right 
angles  to  these  follows,  and  if  necessary  a third  transverse 
layer,  and  so  on  until  the  required  height  of  road  bed  is 
attained.  Stout  stakes  or  pickets  are  driven  through  the 
entire  thickness  of  fascines  to  keep  them  firmly  in  place,  or, 
the  withes  may  be  cut  after  each  layer  is  in  position,  so  as 
to  allow  the  brushwood  to  assume  the  form  of  a layer  of 
uniform  compactness.  The  top  layer  should  be  placed 
transversely  to  the  line  of  the  road.  Having  prepared  the 
foundation  in  this  manner  the  road  covering  is  placed  upon 
it  in  the  usual  way.  If  deemed  necessary,  cross  blind-drains 
leading  to  the  side  ditches,  may  be  introduced  under  the  bed 
of  fascines  in  order  to  secure  deeper  sub-drainage. 

Roads  over  Tidal  Marshes. 

Roads  constructed  over  marshes  which  are  subject  to 


ROADS  OVER  TIDAL  MARSHES. 


61 


daily  overflow  from  the  tides,  may  be  effectively  drained, 
down  to  the  level  of  ordinary  low 
water,  by  a very  simple  system  of 
sluice-gates.  The  ordinary  case  is 
where  the  road  crosses  a tidal  stream 
and  then  traverses  the  marsh  border- 
ing thereon.  Under  such  circum- 
stances, the  earth  excavated  in  cut- 
ting the  two  parallel  side  ditches, 
should  be  formed  into  a dike  or  levee 
on  the  outer  side  of  each  ditch  and 
high  enough  to  exclude  high  water. 

The  ends  of  these  dikes  should  be 
connected,  along  the  margin  of  the 
stream  where  the  road  joins  the  bridge, 
by  a dike  of  the  same  height,  thus 
surrounding  the  roadway  and  side 
ditches  with  a continuous  impervious 
bank  of  earth,  rising  above  high 
water  level. 

Pipes  of  wood  or  iron,  provided 
with  valves  on  the  outer  end  open- 
ing outward,  are  then  inserted,  at  the 
level  of  low  tide,  through  the  dike 
which  separates  the  ends  of  the  side 
ditches  from  the  tidal  stream.  The 
water  flows  out  through  these  pipes 
whenever  the  tide  level  outside  is 
below  the  water  level  in  the  ditches. 

When  the  reverse  ensues  the  gates 
are  closed  by  the  external  pressure  ^ 
of  the  water,  and  all  inward  flow  0\ 


h 


' I **  > 

'll 


iudinal  Bik 


52 


ItOADS,  STREETS,  AND  PAVEMENTS. 


prevented.  Hence  the  water  in  the  ditches  remains  at 
the  level  of  low  tide,  and  the  surface  of  the  road  should 
be  established  at  such  height  above  that  level  that  it 
will  always  be  firm  and  solid.  Whatever  level  may  be 
adopted  for  the  roadway  across  the  marsh,  it  must  on 
approaching  the  stream  rise  to  the  top  of  the  dike  to  prevent 
overflow  from  the  stream  at  that  point.  This  point  is  illus- 
trated in  Fig.  17,  which  is  a longitudinal  section  through 
the  sluice-pipe.  The  road  is  built  a little  higher  than  the 
natural  surface,  and  ascends  to  the  crest  of  the  dike,  near 
the  stream.  The  bridge  across  the  stream  in  continuation 
of  the  road  is  not  shown. 

This  method  of  drainage  has  been  very  successfully 
applied  in  reclaiming  the  “Jersey  Flats”  between  the  cities 
of  Newark  and  Jersey  City,  New  Jersey,  a large  tract  of 
marsh  land  with  its  natural  surface  not  higher  than  the 
level  of  ordinary  high  tide,  and  in  large  part  some  inches 
below  that  level.  These  Flats  were  formerly  subject  to 
twice  daily  overflow,  from  the  Passaic  and  Hackensack 
rivers,  in  which  the  mean  rise  and  fall  of  the  tide  is  about 
4 feet.  The  tract  was  surrounded  by  a dike  or  levee  formed 
along  the  margin  of  the  stream,  of  the  material  excavated 
from  a wide  open  ditch  parallel  to  it  on  the  inside.  Numer- 
ous broad  cross  ditches,  dividing  the  marsh  into  parallelo- 
grams, lead  into  this  main  ditch.  The  sluices  are  located 
at  suitable  intervals  so  as  to  drain  from  the  main  ditch  into 
both  the  Hackensack  and  the  Passaic  rivers.  The  pipes 
are  usually  placed  in  pairs,  and  are  of  various  sizes,  in  only 
a few  instances  exceeding  two  feet  in  interior  diameter.  It 
has  been  found  that  a difference  of  one  inch  in  the  inside 
and  outside  water  level,  will  open  or  close  the  sluice-gates. 


SIDE  DRAINS  AND  DITCHES. 


53 


\\\m 

!i# 

iiAii 


By  this  means  a noxious  swamp  has  been  converted  into 
arable  and  thrifty  land.  It  is  sufficient- 
ly firm  to  support  a roadway  upon 
its  surface,  without  any  special  pre- 
cautions in  preparing  the  road  bed. 

When  the  embankment  requires 
more  earth  than  the  excavation  can 
supply,  the  deficiency  is  made  up  from 
side-cuttings , made  in  some  convenient 
locality  near  by.  On  the  other  hand 
when  the  embankments  do  not  con- 
sume all  the  earth  furnished  by  the 
excavations,  the  excess  is  deposited  in 
spoil-banks , usually  located  on  a some- 
what lower  level  than  the  road  sur- 
face,  care  being  taken  to  provide  for  ? 

1-4. 

the  drainage  in  such  a manner  as  to  90 
prevent  the  formation  of  pools  of  water 
that  might  affect  the  stability  of  the 
side  slopes  of  the  excavations. 

Side  Drains. 

It  is  essential  to  the  proper  condi- 
tion of  a road,  that  the  surface  water 
of  the  soil  adjacent  thereto  shall  be 
cut  off  by  suitable  open  side  drains,  so 
that  it  can  not  filter  under  the  road- 
way, and  render  the  subsoil  soft, 
spongy,  and  incapable  of  sustaining 
the  weight  upon  it.  Otherwise  the  road 
covering  would  sink  into  the  soft  earth  beneath,  and  require  to 


|yi///ib|L 

Jtad.  ^llil 


54 


ROADS,  STREETS,  AND  PAVEMENTS. 


be  frequently  renewed.  In  flat  and  level  countries,  the  side 
drains  (Fig.  18),  should  be  at  least  two  and  a half  to  three  feet 
lower  than  the  bottom  of  the  road  covering,  and,  to  prevent 
accidents  to  vehicles,  they  should  be  placed  on  the  field  side 
of  the  fences  or  hedges,  when  passing  through  sections  of 
country  where  such  barriers  are  necessarjq  as  they  usually 
are  in  agricultural  districts.  It  would  be  better  for  the  road- 
way, to  place  the  side  ditches  between  the  road  and  the 
fences,  thus  widening  the  space  between  the  latter,  and  in- 


Fig.  19. 

creasing  the  degree  of  exposure  of  the  road  surface  to  the 
action  of  the  wind  and  sun  ; and  this  method  should  be  fol- 
lowed whenever  admissible.  A line  of  hedge  or  shade  trees 
on  each  side  of  the  road,  exerts  a very  damaging  effect  upon 
its  condition,  and  adds  greatly  to  the  cost  of  its  proper 
maintenance.  High  walls  and  hedges  are  more  objectiona- 
ble than  open  post-and-rail  or  rail  fences. 

Upon  those  portions  of  the  road  in  excavations,  unless  it 
be  through  rock,  open  side  ditches  are  inadmissible,  as  they 
would  soon  be  filled  up  by  the  earth  wTashed  down  from  the 
side  slopes.  Covered  side  drains  are  necessary.  They  may 
be  constructed  as  shown  in  Fig.  19,  with  a flooring  of  con- 
crete, flagging  stones,  or  brick,  with  side  walls  of  the  same 
material,  and  covered  with  flagging  stones  or  with  l ricks,  or 


DRAINAGE  OF  ROAD  BED. 


55 


stones  corbeled  out  to  meet  above  the  centre  of  the  drain. 
The  roof  should  be  laid  with  open  joints,  and  then  covered 
with  a layer  of  straw,  hay,  or  fine  brushwood,  upon  which 
a filling  of  fragments  of  stone,  bricks,  or  coarse  gravel  and 
pebbles  is  laid,  so  as  to  allow  the  water  to  filter  freely 
through,  without  carrying  sediment  with  it. 

Cross  Drains. 

Besides  the  covered  side  drains  in  cuttings,  cross  drains 
are  usually  deemed  necessary  to  keep  the  road  bed  dry. 
Their  depth  should  be  20  to  24  inches  below  the  road  cover- 
ing. They  should  have  an  inclination  on  the  bottom,  from 
the  axis  of  the  road  to  the  side  drains,  of  not  less  than  1 in 
100  nor  greater  than  1 in  30.  When  the  road  is  level  they 
may  run  straight  across.  When  otherwise,  their  plan 
assumes  the  form  of  a broad  letter  V,  with  the  point  in  the 
centre  of  the  road  directed  toward  the  ascent.  From  this, 
their  usual  form,  they  are  termed  cross-mitre  drains.  Their 
distances  apart  will  depend  upon  the  nature  of  the  soil,  and 
the  kind  of  road  covering  used.  In  some  cases,  it  should  not 
exceed  18  to  20  feet,  in  others  it  may  be  much  greater. 
They  are  constructed  by  digging  trenches  across  the  road 
bed,  after  the  surface  has  been  prepared  for  the  reception  of 
the  road  covering,  and  then  filling  the  trench  with  broken 
stone  or  pebbles,  leaving  a small  open  water-way  at  the  bot- 
tom, so  constructed  that  it  will  not  become  choked  with 
earth.  Bricks  may  be  used  for  this  purpose  in  a variety  of 
ways  as  shown  in  Figs.  20,  21,  22  and  23.  Flat  stones  may 
be  used  as  shown  in  Fig.  9,  page  41. 

The  area  of  the  water-way  of  Fig.  20,  is  unnecessarily 
large,  for  most  cases  that  will  occur  in  practice,  being  16 


56 


ROADS,  STREETS,  AND  PAVEMENTS. 


square  inches.  The  bottom  of  the  road  material  rests  on  the 
line  AB.  Small  drains  placed  close  together  will  drain  the 


Fig.  20. 

road  bed  much  more  efficiently  than  larger  ones  of  the  same 
aggregate  water-way  placed  farther  apart.  A water-way  of 
2.5  to  4 inches  sectional  area,  such  as  may  be  obtained  with 


three  lines  of  whole  bricks  placed  end  to  end  as  in  Fig  22, 
will  generally  be  ample.  The  full  lines  show  one  method  of 


Fig.  23. 

arranging  tne  brick,  and  the  dotted  lines  another.  By  split- 
ting one-third  of  the  bricks  into  halves  longitudinally,  they 


DRAINAGE  OF  ROAD  BED. 


57 


may  be  placed  as  in  Pig.  23,  or  more  economically  still  as  in- 
Fig.  21,  by  splitting  one-fifth  of  them. 

The  water-way  may  be  formed  of  drain  tiles  of  1<^  to  2 
inches  interior  diameter.  Indeed,  the  ordinary  method  of 
tile-drainage  for  agricultural  purposes  will  answer  excellently 
for  the  sub-drainage  of  roads,  and  it  will  seldom  be  neces- 
sary to  use  tiles  of  larger  bore  than  1-J-  to  2 inches.  With  a 
fall  of  1 foot  in  100,  a 1 % inch  tile  will  discharge  nearly 
12,000  gallons  of  water,  and  a 2 inch  tile  nearly  22,890  gal- 
lons in  24  hours.  The  tiles  are  placed  in  contact,  end  to 
end,  in  a trench  cut  very  narrow  at  the  bottom,  care  being 
taken  to  give  each  piece  a firm  bed,  and  to  arrange  the  axes 
in  a continuous  line,  so  as  not  to  diminish  the  water-way  by 
jogs  at  the  joints.  The  bricks,  stones  or  tiles  used  to  form 
the  water-way,  should  be  covered  over  with  a layer  of  hay, 
straw,  tan-bark,  turf,  or  other  suitable  material,  to  prevent 
earth  from  entering  the  drain  ; the  trench  is  then  filled  up 
with  the  earth  excavated  from  it. 

Cost  of  Stone,  Brick  and  Tile  Drains. 

Tiles  are  generally  a little  more  than  one  foot  in  length, 
so  that  making  a fair  allowance  for  breakage  and  imperfect 
pieces  1000  tiles  may  be  relied  upon  to  lay  1000  feet 
of  drain.  Two-inch  tiles  can  be  manufactured  at  profit  in 
ordinary  times  for  $11.00  to  $11.50  per  thousand,  and  bricks 
for  $6.50  to  $7.00  per  thousand.  We  will  estimate  the  tiles 
at  $14.00  and  the  bricks  at  $8.00  delivered  and  distributed 
along  the  road.  A cross  drain  under  a road  30  feet  wide, 
with  one  foot-path,  page  60,  will  be  about  45  feet  long.  The 
tiles  will  cost  $0.63  for  each  cross  drain,  the  brick  $1.35  for 
the  small  triangular  drain,  Fig.  21  ; $1.62  for  the  triangu- 
3* 


58 


ROADS,  STREETS,  AND  PAVEMENTS. 


lar  drain  Fig.  22,  or  the  small  square  drain,  Fig.  23,  and  $3.24 
for  the  large  square  drain,  Fig.  20.  The  labor  will  be  nearly 
proportional  to  the  amount  of  excavation,  and  will  therefore 
be  the  least  for  the  tile  drain,  so  that  it  is  within  limits  to 
estimate  the  cost  of  the  latter  in  labor  and  material,  at  con- 
siderably less  than  one-half  that  of  the  former.  If  the  cross 
drains  have  their  discharge  three  inches  above  the  bottom 
of  the  side  ditches,  with  a fall  from  the  centre  of  the 
roadway  each  way  of  three  inches — equal  to  1 in  90 — 
their  average  depth  below  the  road  surface  will  be  about 
three  feet,  and  the  average  depth  of  excavation  below  the 
subgrade  prepared  for  the  reception  of  the  road  materials 
will  be  a little  over  two  feet,  inclusive  of  the  greater  depth 
under  the  foot-path.  The  following  estimates  of  the  cost 
per  rod  of  these  several  kinds  of  drains,  is  believed  to  be 
fair,  with  labor  at  $1.75  per  day,  in  stiff  clay  soils  : 


Tile  drain. 

2-inch  pipe 
tiles. 

Brick  tri- 
angular 
drain. 

Fig.  21. 

Brick  drain. 

3 courses 
end  to  end. 

Figs.  22, 23. 

Brick  drain. 
4-in.  x 4-in. 
Fig.  20. 

Catting  and  filling 

$ cts. 

$ cts. 

$ cts. 

$ cts. 

per  rod 

.25 

.30 

. 30 

. 35 

Cost  of  tiles,  or  bricks 

.23 

.55 

.594 

1.188 

Total  cost  per  rod . . . 

.48 

.85 

.894 

1.538 

The  trenches  for  stone  drains  must  be  excavated  to  a 
width  of  at  least  21  inches  on  the  bottom.  They  maybe 
cut  with  vertical  sides.  At  least  one-half  of  the  earth  must 
be  hauled  away  to  make  room  for  the  stone,  so  that  there 


DRAINAGE  OF  ROAD  BED. 


59 


will  be  more  than  one  cubic  yard  of  earth  to  be  carried  away 
and  a like  amount  of  stone  collected  and  brought  to  the 
road  for  every  rod  of  drain.  If  stones  of  the  right  kind  are 
near  at  hand  it  would  not  cost  more  than  25  cents  per  cubic 
yard  to  collect  them,  while  twice  that  amount  would  not  be 
excessive  if  they  have  to  be  brought  from  a distance  or  dug 
from  a bank  or  pit.  Assuming  that  the  stones  can  be  col- 
lected within  a quarter  of  a mile  of  the  road,  the  following 
estimate  is  submitted  as  a near  approximation  : 

Cost  of  Stone  Drains  per  lineal  rod. 


Cutting  trench  and  hauling  away  the  surplus  earth 50  cents, 

Collecting  and  hauling  1 cubic  yard  of  stone 25  “ 

Laying  the  stone  and  filling  in.  25  “ 

Total  per  lineal  rod $1.00 


A standard  work  on  Farm  Drainage  (Henry  F.  French) 
estimates  that  with  tiles  at  $10.00  per  M, — 1 cent  per  foot — 
and  labor  at  $1.00  per  day,  the  cost  of  a tile  drain  4 feet 
deep  will  be  for  cutting  and  filling  33^  cents,  and  for  the 
tiles  16-f  cents,  or  a total  of  50  cents  per  rod.  At  the  same 
price  for  labor,  the  cost  of  a stone  drain  is  set  down  at 
$1.25  per  rod,  viz.,  for  cutting  and  filling  trench  21  inches 
wide  50  cents,  for  hauling  stone  50  cents,  and  for  laying  the 
same  25  cents.  And  the  conclusion  is  that  “ drainage  with 
tiles  will  generally  cost  less  than  one-half  the  expense  of 
drainage  with  stones,  and  be  incomparably  more  satisfactory 
in  the  end.” 

As  tile  drains  are  more  liable  to  injury  from  frost  than 
those  of  either  bricks  or  stones,  their  ends  at  the  side 
ditches  should  not,  in  very  cold  climates,  be  exposed  directly 
to  the  weather,  but  may  terminate  in  blind  drains,  reaching 


GO 


ROADS,  STREETS,  AND  PAVEMENTS. 


under  the  road  a distance  of  aoout  3 to  4 feet  from  the 
inner  slope  of  the  ditch. 

Another  method  of  draining  the  road-bed, 
offering  security  from  frost,  is  by  one  or  more 
longitudinal  drains,  discharging  into  cross-drains 
placed  from  250  to  300  feet  apart,  more  or  less, 
depending  on  the  contour  of  the  ground.  With 
a roadway  and  foot  path  45  feet  wide  at  the  level 
of  the  bottom  of  the  side  ditches,  two  such  drains 
of  1^  to  2 inch  tiles  will  be  required  in  most 
kinds  of  clayey  soils.  They  should  be  placed  at 
equal  distances  from  the  side  ditches  and  from 
each  other,  and  will  therefore  be  15  feet  apart. 
Their  depth  below  the  surface  should  be  not 
^ less  than  3 to  3^  feet,  and  the  cross-drains  into 
H which  they  discharge  should  be  of  ample  di 
mensions. 

All  roads  upon  clayey  soils  in  flat  level  coun 
tries  should  be  amply  provided  with  drain! 
under  the  road  covering.  For  deep,  marshy, 
soils,  as  already  mentioned,  they  are  indis- 
pensable. 


Surface  Drainage. 


than  1 in 


The  drainage  of  the  road-surface  is  provided 
for  by  making  it  a few  inches  higher  in  the  cen- 
tre than  at  the  sides,  sloping  it  gently  in  both 
directions  to  the  side  gutter,  and  is  also  greatlj 
facilitated  by  giving  the  surface  an  inclination 
longitudinally  not  greater  than  1 in  34  nor  less 
125.  A series  of  gentle  undulations  may  be 


SURFACE  DRAINAGE. 


61 


established,  even  in  a perfectly  level  country,  without  adding 
materially  to  the  cost  of  construction. 

If  there  are  no  sidewalks  the  surface  drainage  is  dis- 
charged directly  into  the  side  ditches.  When  there  are 
sidewalks  the  drainage  is  into  the  side  gutters,  from  which 
it  must  be  carried  into  the  side-ditches  by  small  covered 
drains  of  stone,  brick,  or  tile,  see  Fig.  25,  and  dotted  lines, 
Fig.  18,  or  conducted  by  vertical  shafts  into  the  cross- 
drains, if  that  method  of  draining  the  road-bed  has  been 


Fig.  35. 

adopted.  These  vertical  drains  (Fig.  24)  are  covered  at 
top  by  a grating  to  arrest  coarse  earth,  leaves,  etc.,  and  may 
have  beneath  them  a small  vault  lined  with  masonry,  termed 
a silt  basin,  to  collect  the  fine  sediment  which  flows  in  from 
the  roadway,  which  should  be  removed  from  time  to  time 
and  restored  to  the  road  surface. 

The  covered  side-drains  (Fig  19)  may  if  desirable,  be 
constructed  with  a roof  of  concrete  or  of  brick  or  stone  laid 
in  mortar,  in  which  case  the  filling  of  broken  stone,  gravel, 
etc.,  above,  for  filtering  purposes,  would  be  omitted,  and 


62 


ROADS,  STREETS,  AND  PAVEMENTS. 


arrangements  made  for  conducting  the  water  into  the  drain 
through  vertical  shafts  placed  at  suitable  intervals.  These 
vertical  openings  should  be  placed  over  silt-basins,  and  be 
large  enough  to  admit  a boy,  so  that  the  sediment  can  be 
removed  as  often  as  necessary.  (Fig.  25. ) This  method  of 
construction  is  much  used  in  cities  and  towns,  but  not  on 
country  roads. 

Culverts. 

Besides  the  side  gutters,  side  drains,  cross  drains,  and  small 
drains  already  mentioned,  which  are  intended  more  espe- 
cially to  carry  off  the  water  falling  upon  the  roadway,  and 
upon  the  side  slopes  in  cuttings,  and  to  keep  the  road  bed 
and  subsoil  dry  in  flat  countries  where  the  soil  is  clayey  or 
marshy,  other  drains  called  culverts  are  required  for  carry- 
ing under  the  roadway  the  stream  intersected  by  it,  and 
generally  for  conveying  away  into  the  natural  water-courses 
the  water  collected  by  the  side  gutters  and  ditches  on  the 
upper  side  of  the  road. 

The  dimensions  of  the  water-way  of  culverts  should  be 
proportioned  to  the  greatest  volume  of  water  which  they 
may  ever  be  required  to  carry  off,  and  should  in  all  cases  be 
large  enough  to  allow  a boy  to  enter  for  the  purpose  of  clean- 
ing them  out.  Eighteen  inches  square,  or  if  circular,  twenty 
inches  in  diameter,  will  suffice  for  this  purpose.  They 
should  have  an  inclination  on  the  bottom  of  not  less  than  one 
in  one  hundred  and  twenty,  nor  greater  than  one  in  thirty. 
Small  culverts  may  be  constructed  of  the  same  cross-section, 
and  in  substantially  the  same  manner  as  the  covered  side 
drains,  Fig.  19,  with  the  exception  that  no  arrangement  need 
be  made  for  receiving  the  water  from  above  through  a filter 
of  stone  fragments  or  gravel.  The  sides  ai^d  roof  may 


CULVERTS. 


63 


therefore  be  laid  in  mortar,  and  the  floor  had  better  be  in 
the  form  of  an  inverted  arch. 

In  localities  where  stone  and  brick  are  expensive,  small 
culverts  may  be  constructed  of  four  slabs  or  planks  (Fig.  26) 
forming  a long  box  open  at  both  ends.  To  prevent  the  side 
pieces  from  being  forced  together  by  the  pressure  of  the  sur- 
rounding earth,  they  should  rest  against  small  blocks  o t 
wood  nailed  at  intervals  into  triangular  notches  cut  on  the 
inner  faces  of  the  top  and  bottom  pieces,  or  the  edges  of  the 
side  pieces  may  be  inserted  into  longi- 
tudinal grooves  cut  in  the  top  and  bot- 
tom pieces. 

It  will  be  found  advantageous  to  use 
hydraulic  concrete  for  culverts,  especially 
for  those  of  large  dimensions,  unless  bricks 
can  be  procured  at  a low  cost,  or  stone  in 
suitable  form  is  plenty  in  the  neighbor- 
hood. Most  localities  will  furnish  sand, 
coarse  gravel  and  pebbles.  With  these  and 
a liberal  addition  of  common  lime  to  the 
hydraulic  cement,  a concrete  suitable  for 
work  of  this  description  can  be  prepared  at  moderate 
cost.  The  following  proportions  will  answer  : 

1 measure  of  Rosendale,  (or  any  equivalent)  cement. 

1 measure  of  slaked  lime  in  powder. 

4 to  4|  measures  of  clean  sharp  sand. 

9 to  10  measures  of  pebbles,  small  fragments  of  stone  or 
brick,  oyster  shells,  or  a mixture  of  them  all. 

When  Portland  cement  of  standard  quality  is  used,  the 
proportions  may  be  : 

1 barrel  Portland  cement,  as  packed  for  market, 


Fio.  26. 


54 


ROADS,  STREETS,  AND  PAVEMENTS. 


1 barrel  common  lime,  producing  2 £ to  2f  barrels  slaked 
lime  powder. 

9 to  10  barrels  sand. 

15  to  17  barrels  of  the  coarse  materials. 

It  must  be  borne  in  mind  that  the  addition  of  common 
lime  weakens,  and  also  retards  the  induration  of  the  con- 
crete. The  quantity  added  must,  therefore,  be  governed  by 
the  importance  of  the  work,  and  the  length  of  time  it  will 
have  to  harden  before  being  subjected  to  heavy  weight  or 
pressure. 

A form  of  cross-section  for  culverts,  which  admits  a min- 


imum thickness  in  the  concrete  floor  and  sides  is  shown  in 
Fig.  27.  In  constructing  a culvert  of  this  form,  a trench, 
concave  at  bottom,  is  first  excavated  to  the  width  of  the  base 
a c,  and  the  concrete  floor,  four  to  five  inches  in  thickness,  is 
formed  thereon  in  one  layer.  Upon  the  floor  cross  pieces  are 
placed  at  intervals  of  a few  feet,  to  support  the  two  detached 
segments  of  centering  for  the  sides,  which  should  rest  upon 
wedges,  to  facilitate  their  removal  for  further  use.  The 
centering  may  be  made  in  lengths  of  from  twelve  to  twenty 
feet,  and  of  such  weight  that  three  or  four  men  can  easily 


CULVERTS. 


65 


nandle  them.  Convexity  is  given  to  the  exterior  surfaces  by 
a movable  form,  made  by  nailing  narrow  strips  of  boards  to 
cross  pieces  cut  to  the  required  concavity.  It  is  kept  in 
place  by  wooden  braces  nailed  to  stakes  driven  into  the  side 
slopes  of  the  trench.  For  a culvert  of  twenty-four  inches 
interior  width  at  the  base,  arched  as  in  Fig.  27,  with  circular 
segments  whose  centres  are  in  the  vertices  of  the  opposite 
angles,  the  sides  need  not  exceed  five  to  six  inches  in  thick- 
ness, in  case  of  ordinary  depth. 

For  culverts  with  a gentle  inclination  on  the  bottom,  the 
concrete  floor  may  generally  be  safely  replaced  by  a layer 
three  to  four  inches  in  thickness 
of  broken  stone  or  pebbles  of 
half  an  inch  to  two  inches  in 
diameter,  grouted  with  hy- 
draulic cement  to  keep  them 
in  place,  and  protect  the  founda- 
tion from  undermining.  For 
the  same  reason,  the  foundations 
should  be  started  lower  than 
when  the  bottom  of  the  water 
way  is  well  paved,  or  when  formed  of  a monolith  of  concrete 
in  the  manner  last  described.  For  the  discharge  of  large 
volumes  of  water,  the  masonry  must  be  proportionally  mass- 
ive, but  may  still  be  made  of  concrete,  which  may  be  con- 
siderably cheapened  by  embedding  in  it,  as  the  work  pro- 
gresses, fragments  of  rock  of  various  shapes  and  sizes.  A 
section  of  such  a work  is  shown  at  Fig.  28. 

The  ends  of  culverts  passing  through  embankments 
should  be  protected  against  the  undermining  action  of  the 
water.  This  may  be  done  by  a sheet  piling  of  flagging- 
stones  or  stout  planks,  sunk  well  into  the  soil,  or,  by  an 


66 


HOADS,  STREETS,  AtfD  t»A  VRMEHT8. 


apron  of  rip-rap  stone,  or  a good  pavement,  so  as  to  prevent 
all  percolation  of  water  under  or  at  the  sides  of  the  culvert. 
The  length  of  the  covered  portion  of  a culvert  is  equal  to 
the  distance  through  the  embankment,  on  a line  with  tho 
crown  of  the  arch  or  roof,  and  it  should  be  extended  out  and 
finished  at  each  end  by  two  wing  walls  spread  out  in  fan 
shape,  and  finished  on  top  in  steps,  by  courses  or  in  a sur- 
face parallel  with  the  side  slope,  but  rising  a few  inches 
above  it,  to  prevent  the  earth  washing  over. 

In  order  to  give  greater  stability  to  the  wing  walls,  and 
increase  the  power  to  resist  the  pressure  of  the  earth  behind 
them,  their  plan  may  be  that  of  an  arc,  with  either  the  con- 
vexity or  concavity  to  the  front,  the  object  being  simply  to 
increase  the  moments  of  inertia  without  materially  increas- 
ing the  amount  of  masonry  in  the  wall.  One  end  of  the 
culvert  given  in  transverse  section  in  Fig.  28,  is  shown  with 
wing  walls  in  longitudinal  vertical  section  and  elevation  in 
Fig.  29,  and  in  horizontal  section  and  plan  in  Fig.  30. 

Width  and  Transverse  Form  of  Roads. 

The  determination  of  the  width  and  transverse  form 
of  a country  road  presents  questions  of  great  import- 
ance. Some  engineers  recommend  narrow  roads,  on  the 
erroneous  presumption  that  the  cost  of  maintenance,  like  that 
of  construction,  varies  directly  or  nearly  so  with  the  area  of 
the  road  surface,  while  in  point  of  fact,  unless  in  special  and 
extreme  cases,  it  varies  with  the  amount  of  traffic  upon  it, 
increasing,  however,  more  rapidly  than  the  traffic.  It  may 
be  assumed  that  the  quantity  of  material  required  to  repair 
a road  is  about  the  same,  for  the  same  amount  of  traffic, 
whether  the  road  be  twenty-five  feet  or  thirty  feet  in  width, 


CULVERTS. 


(tt 


although  there  is  a small  saving  in  the  labor  of  spreading  it, 
in  favor  of  the  narrow  road.  A narrow  road  is  less  exposed 


bo  the  drying  action  of  the  wind  and  sun  than  a wide  one, 
and  also  requires  more  constant  supervision  and  more  fre- 


68 


HOADS,  STREETS,  AND  PAVEMENTS. 


quent  repair,  in  consequence  of  the  traffic  being  more  closely 
restricted  to  one  track. 

A width  of  27  to  30  feet,  prepared  for  vehicles,  will  be 
ample  for  the  principal  thoroughfare  between  cities  and 
large  towns,  which  should  be  increased,  within  or  near  the 
cities,  to  40,  50,  or  even  to  60  feet,  where  the  amount  of 
traffic  is  large,  and  there  is  a great  deal  of  light  travel  and 
pleasure  driving. 

For  cross,  branch,  and  ordinary  town  and  country  roads, 
the  width  of  the  portion  bedded  with  stone  may  usually  be 
reduced  to  from  16|-  to  17  feet,  which  will  amply  suffice  for 
two  carriages  of  the  widest  usual  size  to  pass  each  other  upon 
the  road-covering  without  danger  of  collision.  In  specia1 
cases  of  private  roads  where  the  bulk  of  heavy  traffic  is  all  in 
one  direction,  the  width  of  covering  may  be  restricted  to 
8 or  9 feet,  or  what  is  sufficient  for  one  carriage,  the  loaded 
vehicles  having  the  right  of  way,  and  requiring  those  travel 
ing  light  to  turn  out  upon  the  sides. 

Side-walks  for  foot  passengers  are  usually  omitted  m new 
or  thinly  settled  countries,  although  always  desirable,  if  for 
no  other  reason  than  the  protection  they  afford  against  up- 
setting into  the  side  ditches  during  the  night,  in  localities 
where  there  are  no  fences,  or  where  the  ditches  are  between 
the  fences  and  roadway. 

At  least  one  paved  or  otherwise  properly  covered  side- 
walk is  necessary  near  towns  and  villages.  When  the 
natural  soil  is  composed  principally  of  sand  and  gravel  it 
may  form  the  surface  of  the  side-walk,  which  should  be 
established  at  about  the  height  of  the  centre  of  the  roadway. 
In  heavy  clayey  or  loamy  soils  an  excavation  to  the  depth  of 
five  or  six  inches  should  be  made  to  the  proper  width  of  the 


THE  WIDTH  OF  KOADS. 


69 


foot-path,  and  filled  in  with  coarse  sand  or  gravel,  or  with  a 
layer  of  well-compacted  broken  stone  topped  off  with  one  to 
two  inches  of  gravel.  The  inner  edge  of  the  side-walk  should 
be  protected  against  the  wash  of  the  side-gutters  by  a facing 
of  sods  or  dry  stone. 

In  cities  the  side-walks  are  paved,  and  the  surface  slopes 
toward  the  street  at  the  rate  of  not  less  than  one  inch  in  ten 
feet,  in  order  to  secure  the  prompt  discharge  of  the  surface 
water  into  the  side-gutters,  and  the  edge  next  the  gutters  is 
faced  with  slabs  of  stone  called  curl-stones  set  on  edge,  with 
their  top  edges  flush  with  the  side-walk  pavement,  and  their 
lower  edge  six  to  eight  inches  below  the  bottom  of  the  gutter. 

(The  construction  of  side-walks  will  be  described  here- 
after). 

In  France,  four  classes  of  roads  are  prescribed  as  fol- 
lows : First,  66  feet  wide  of  which  22  feet  in  the  middle  are 
paved  or  stoned.  Second,  52  feet  wide  of  which  20  feet  are 
stoned.  Third,  33  wide  of  which  16  feet  in  the  middle  are 
stoned  ; and  fourth,  a width  of  26  feet  of  which  16  feet  in  the 
middle  are  stoned. 

Telford’s  Hollyhead  road,  which  runs  through  a hilly 
country,  is  32  feet  wide  between  the  fences  on  flat  ground,  28 
feet  on  side  cuttings  not  exceeding  three  feet  deep,  and  22 
feet  along  steep  and  precipitous  ground. 

The  Cumberland  or  National  road  in  the  United  States 
has  a prescribed  width  of  80  feet,  but  the  prepared  road- 
way is  only  30  feet  wide. 

The  Roman  Military  roads  were  narrow,  being  only  12 
feet  wide  on  the  straight  portions,  and  16  feet  upon  curves. 

Wide  roads  are  sometimes  finished  with  a road-cover- 
ing in  the  middle  only,  of  just  sufficient  width  for  the  velr 


70  ROADS,  STREETS,  AND  PAVEMENTS. 

cles  to  pass  each  other  upon  it,  while  the  sides  are  main- 
tained as  dirt  roads , for  light  and  fast  travel  during  the  sea- 
son when  the  soil  is  comparatively  dry  and  firm.  The  objec- 
tion to  this  method  is  that  during  the  wet  season  the  road 
covering  is  injured  by  the  large  quantity  of  mud  conveyed  to 
it  from  the  sides. 

Opinions  differ  as  to  whether  that  portion  of  the  carriage 
way  to  be  finished  and  maintained  as  a dirt  road,  should  be 
at  the  sides  or  in  the  middle.  Heavy  loads  are  apt  to  seek  the 
sides,  in  order  that  the  driver  may  walk  upon  the  foot  path, 
which  favors  metaling  the  wings  rather  than  the  middle. 

It  has  been  mentioned  that  the  drainage  of  the  road 
should  be  provided  for  by  making  it  higher  in  the  middle, 
and  also  by  sloping  it  longitudinally.  Engineers  differ  as  to 
the  most  advantageous  form  of  cross-section,  some  recom- 
mending a convex  curve  approaching  to  a segment  of  a cir 
cle,  or  a semi-ellipse,  while  others  prefer  two  planes  gently 
sloping  toward  the  side-gutters,  and  meeting  in  the  middle 
of  the  road  by  a short  connecting  convex  surface.  The  lat- 
ter method  seems  to  carry  the  weight  of  testimony,  the 
obvious  objections  to  the  convex  road  being  that  the  water 
will  stand  in  the  middle  of  the  road  unless  carried  off  by 
longitudinal  slopes  ; that  carriages  will  keep  in  or  near  the 
middle,  and  cause  excessive  wear  along  one  line,  in  order  to 
run  on  a level  and  avoid  the  tendency  to  overturn  near  the 
side-gutters  ; and  that  when  travel  is  forced  to  take  the  sides, 
the  labor  of  the  horses  and  the  wear  of  the  wheels  and  of 
the  road  covering  are  greatly  increased,  in  consequence  of  the 
oblique  action  of  the  weight,  and  the  tendency  of  the  vehi- 
cle to  slide  upon  the  road  surface. 

It  is  recommended  therefore  that  the  cross-section  of  the 


CATCHWATEES. 


n 


road  surface  be  formed  of  two  straight  inclined  lines  con- 
nected at  the  centre  by  an  arc  of  a circle  about  five  feet  long, 
drawn  to  a radius  of  from  85  to  90  feet.  The  highest  point 
of  the  arc  should  be  in  the  middle  of  the  carriage  way.  The 
degree  of  inclination  toward  the  sides  may  be  at  the  rate 
of  1 in  20  for  rough  roads,  1 in  30  for  ordinary  well-main- 
tained gravel  or  broken  stone  roads,  as  in  Pig.  18,  and  1 in 
40  or  50  for  good  paved  roads.  The  drainage  of  the  surface 
should,  when  practicable,  be  further  facilitated  by  giving  it 
an  inclination  longitudinally  of  not  less  than  1 in  125.  In 
a level  country  this  may  be  done  at  a trifling  cost  by  a 
series  of  short  gentle  undulations. 

Catchwaters. 

Upon  a long  stretch  of  continuously  descending  road, 
catchwaters  should  be  placed  at  intervals.  They  are  also 
necessary  at  the  depressions  where  an  ascending  and  descend' 
ing  grade  meet,  their  province  being  to  collect  the  water 
which  runs  down  the  surface  of  the  road  longitudinally,  and 
convey  it  into  the  side-drains,  thereby  preventing  the  forma- 
tion of  furrows  and  gullies  in  the  road  surface.  They  are 
broad  shallow  paved  ditches  constructed  across  the  road,  and 
so  formed  that  vehicles  can  pass  over  them  without  sustain- 
ing a severe  shock.  They  may  slope  toward  one  of  the  side 
ditches  only,  or  incline  each  way  from  the  centre  toward 
both,  and,  if  located  in  a depression,  will  be  placed  at  right 
angles  to  the  line  of  the  road.  When  placed  upon  a grade 
they  should  cross  the  roadway  diagonally,  in  a straight  line, 
when  their  discharge  is  on  one  side  only,  and  if  on  both, 
fclieir  plan  should  be  that  of  a broad  letter  V,  with  the  angle 
pointing  toward  the  ascent,  so  that  they  will  arrest  and 


72  ROADS,  STREETS,  AND  PAVEMENTS. 

divide  the  surface  water  and  convey  it  to  the  two  side 
ditches. 

The  catehwaters  may  have  a descent  of  from  1 in  30  to 
1 in  40,  and,  as  their  cross-section  should  be  as  nearly  uni- 
form as  possible,  the  direction  to  be  given  to  them  in  relation 
to  the  axis  of  the  road  will  be  governed  by  the  steepness  of 
the  grade  upon  which  they  are  placed,  and  the  transverse 
form  of  the  road  surface.  They  should  never  be  so  located 
that  one  rear  wheel  and  one  forward  wheel,  on  opposite  sides 
of  a vehicle,  will  enter  them  at  the  same  time. 

A mound  of  earth  erected  across  the  road,  either  in  a 
straight  line,  or  in  a V shape  pointing  up  the  ascent,  is  a 
cheap  substitute  for  a catch  water  drain,  and  will  answer 
very  well  if  so  proportioned  that  vehicles  can  pass  it  without 
inconvenience  and  with  very  little  shock. 

The  pavement  of  catehwaters  should  extend  to  the  point 
where  the  surface  water  is  received — by  the  side-ditches 
or  otherwise — to  be  conveyed  away  to  the  natural  water- 
courses. 

Tools  and  Implements. 

The  most  necessary  small  tools  and  implements  used  in 
the  construction  and  repair  of  roads  are  hammers  for  break- 
ing stone,  forks  for  handling  it,  levels  for  adjusting  the 
transverse  form  of  the  surface,  and  shovels  and  picks  for 
general  use. 

The  stone  hammers  are  made  of  iron  or  steel,  with 
wooden  handles,  and  are  of  two  sizes,  one  to  be  used  sitting 
and  the  other  in  a standing  posture.  The  first  has  a head  5.} 
to  6 inches  long,  weighing  about  1 pound,  fixed  to  a handle 
18  inches  long.  The  other  hammer  head  weighs  2 pounds  and 


TOOLS  AND  IMPLEMENTS. 


73 


may  be  7 inches  long,  and  has  a handle  about  3}  feet  long. 
See  Fig.  31. 

The  fork  (Fig.  32)  used  in  taking  up  the  stones  from 
the  pile  to  load  them  into  barrows  or  carts,  or  spread  them 
upon  the  road,  is  made  with  ten  or  eleven  stout  steel  prongs 
each  13  to  14  inches  in  length,  set  with  their  points  1£  to 


Fig.  31. 


1^-  inches  apart.  The  whole  length  of  the  fork  inclusive  of 
handle  should  be  about  4 feet  8 inches.  Broken  stone  can  be 
taken  up  with  greater  ease  and  rapidity  with  a fork  than 
with  any  kind  of  shovel,  leaving  the  detritus  and  earthy 
matter  behind. 

The  pick  is  the  one  in  common  use,  consisting  of  a bent 


Fig.  32. 


iron  head  tipped  with  steel  at  both  ends  and  weighing  about 
10  pounds,  set  to  an  ash  handle  about  2 J feet  long.  One  tip 
in  fashion  like  an  adz,  and  the  other  into  a blunt  point. 

The  ordinary  pointed  shovel , with  a concave  blade  and  a 
bent  wooden  handle,  is  the  most  useful  kind  for  road  pur- 
poses. 


n 


ROADS,  STREETS,  AND  PAVEMENTS. 


The  level , Fig.  33,  is  of  great 


Side  Drain 


Afidd  (e  of  Roa  d. 


value  in  adjusting  the 
cross-section  of  t*he  road. 
It  consists  of  a wooden 
straight  edge  A 0 with 
a plummet  D at  its  cen- 
tre. For  a road  30  feel 
wide  between  the  side 
gutters,  the  straight  edge 
should  be  16  feet  long, 
which,  omitting  6 inches 
at  each  end,  may  be  divi 
ded  into  equal  spaces-  - 
say  five  spaces  of  3 fe  it 
each.  Sliding  gauges, 
set  transversely  in  dove 
tail  grooves,  are  placed  at 
the  several  points  of  divi- 
sion, omitting  one  at  the 
end  of  the  straight  edge 
intended  to  rest  directly 
on  the  centre  of  the  road. 
By  placing  the  level  trans- 
versely across  one  half  of 
the  road,  with  the  end, 
not  occupied  by  a gauge, 
resting  on  the  road  sur- 
face at  the  crown,  or  at 
the  precise  height  1 o 
which  the  crown  is  to 
be  finished,  and  then  mak- 


THE  LEVEL. 


75 


ing  the  straight  edge  horizontal  by  the  plummet,  the  lower 
ends  of  the  several  gauges — previously  adjusted  and  fixed  to 
the  required  transverse  slope — will  indicate  five  points  of  the 
required  road  surface,  the  outer  point  being  the  bottom  ol 
the  side  gutter. 


chapter  m. 


ROAD  COVERINGS. 

Road  Coverings,  have  for  their  object  the  reduction  oi 
the  force  of  traction  to  the  lowest  practicable  limit,  at  the 
least  cost  for  construction  and  maintenance.  They  should  be 
composed  of  hard,  tough  and  durable  materials,  laid  upon  a 
firm  bed,  or  upon  an  artificial  foundation,  from  which  water 
is  excluded  by  suitable  drainage. 

The  basaltic , the  doleritic  and  other  trap  rocks,  known 
also  as  green  stone,  the  sienitic  granites,  and  generally  the 
hardest  and  toughest  of  the  feldspathic  rocks,  and  some  of 
the  limestones  of  the  transition  and  carboniferous  formations, 
furnish  the  most  valuable”  road  coverings,  whether  used  in 
the  form  of  rectangular  blocks,  or  in  small  angular  frag- 
ments, or  as  cobble-stones,  gravel,  or  coarse  sand.  Slag 
from  blast  furnaces,  and  cinders  and  clinker  from  cement 
kilns,  are  also  used  for  this  purpose. 

Wood  in  the  form  of  blocks,  or  sawn  into  planks  or  slabs, 
is  sometimes  employed  for  the  road-surface,  but  with  little 
satisfaction  or  advantage.  Its  employment  for  foundations 
is  sometimes  expedient  and  even  necessary  in  the  absence  of 
better  materials. 

The  covering  of  most  of  the  roads  in  the  United  States, 
and  in  all  new  countries,  is  the  natural  soil  excavated  from 
the  side  ditches  and  thrown  into  the  middle  of  the  roadway. 
In  many  cases,  especially  in  sandy  or  gravelly  soils,  even 


CLASSIFICATION  OF  ROADS. 


7? 


the  side  ditches  are  omitted,  and  the  road  is  simply  a wagon 
track  upon  the  natural  surface,  which  soon  becomes  a broad 
shallow  ditch,  collecting  and  retaining  the  surface  water  from 
both  sides  of  the  track. 

Classification  of  Roads. 

Country  roads , as  distinguished  from  paved  streets  in 
cities  and  towns,  may  be  classified  with  respect  to  their  cov- 
erings as  follows  : 

1.  Earth  roads. 

2.  Corduroy  roads. 

3.  Plank  roads. 

4.  Gravel  roads. 

5.  All  broken  stone  (or  Macadam)  roads. 

6.  Stone  sub-pavement,  with  top  layers  of  broken  stone 
(Telford). 

7.  Stone  sub-pavement  with  top  layers  of  broken  stone 
and  of  gravel. 

8.  Stone  sub-pavement  with  top  layers  of  gravel. 

9.  Rubble-stone  bottom  with  top  layers  of  broken  stone, 
gravel,  or  both. 

10.  Concrete  sub-pavement  with  top  layers  of  broken 
stone,  gravel,  or  both. 


Earth  Roads. 

Earth  roads  necessarily  possess  so  many  defects  of  sur- 
face, that  whatever  amelioration  their  condition  is  suscepti- 
ble of,  by  a careful  attention  to  grade,  surface-drainage,  and 
sub-drainage,  should  be  secured.  The  grades  should  be  easy, 
not  exceeding  1 in  30,  the  road  surface  should  slope  not  less 
than  1 in  20  from  the  centre  toward  the  sides,  the  side 


78 


ROADS,  STREETS,  AND  PAVEMENTS. 


ditches  should  be  deep  and  capacious  with  a fall  of  not  less 
than  1 in  120,  and  trees  should  be  removed  from  the  borders 
to  admit  the  wind  and  sun.  In  soils  composed  of  a mixture 
of  sand,  gravel  and  clay,  the  road  is  formed  of  this  material, 
and  requires  only  that  the  ditches  should  be  kept  open  and 
free,  and  that  the  ruts  and  hollows  be  filled  up  as  fast  as  they 
form  in  the  surface,  in  order  to  render  the  road  a good  one 
of  its  kind. 

In  loose  sandy  soils,  a top  layer  six  inches  thick,  of  tough 
clay  will  be  an  effective  method  of  improvement,  which,  to 
save  expense,  may  be  restricted  to  one-half  the  width  of  the 
roadway.  Sand  may  be  added  to  adhesive  clay  soils  with 
equal  benefit,  the  object  in  either  case  being  to  produce  an 
inexpensive  road-covering  that  will  pack  under  the  action  of 
the  traffic  during  the  dry  season,  and  will  not  work  up  into 
adhesive  mud  in  rainy  weather. 

The  material  used  in  filling  up  ruts  and  hollows  should 
be  composed  largely  of  gravel  and  coarse  sand,  free  from  sod, 
muck  and  mould.  It  should  not  contain  cobble-stones,  or 
larger  fragments  of  rocks,  which  would  form  hard  and  un- 
yielding lumps  on  one  side  of  the  wagon  track,  soon  result- 
ing in  corresponding  ruts  and  hollows  on  the  other.  All 
ruts  should  be  filled  in  with  good  materials  as  soon  as 
formed. 

A pernicious  custom  prevails  throughout  a large  portion 
of  the  United  States,  of  repairing  country  roads  only  at  cer- 
tain seasons  of  the  year.  The  cost  of  maintenance  would 
be  greatly  reduced  by  frequent  repairs,  and  especially  by 
keeping  the  side-ditches  clear  and  open  to  their  full  width 
and  depth,  by  promptly  filling  in  the  ruts,  and  by  maintain- 
ing the  required  slopes  from  the  centre  toward  the  sides.  It 


CORDUROY  ROADS. 


79 


will  seldom  be  found  that  the  material  obtained  by  cleaning 
out  the  side-ditches  is  fit  to  put  upon  the  roadway. 

Corduroy  Roads. 

Straight  logs  of  timber  either  round  or  split,  if  cut  to 
suitable  lengths  and  laid  down  side  by  side  across  the  road- 
way, scarcely  deserve  the  name  of  road.  They  are  never- 
theless vastly  superior  to  a soft  marsh  or  swamp,  which,  in 
some  seasons  of  the  year,  would  be  absolutely  impassable  for 
wheeled  vehicles  of  any  description.  They  are  commonly 
known  as  corduroy  roads  from  their  ribbed  character.  In 
heavily  timbered  districts  nearly  all  the  logs  for  such  a con- 
struction would  be  procured  in  clearing  off  the  usual  width 
of  4 rods — 66  feet — prescribed  for  most  country  roads,  the 
width  of  the  road-covering  itself,  or  the  corduroy,  being 
restricted  to  about  15  or  16  feet,  so  that  two  vehicles  can 
pass  each  other  upon  it  without  interference.  The  logs  are 
all  cut  to  the  same  length,  which  should  be  that  of  the 
required  width  of  the  road,  and  in  laying  them  down  such 
care  in  selection  should  be  exercised,  as  will  give  the  smallest 
joints  or  openings  between  them.  In  order  to  reduce  as 
much  as  possible  the  resistance  to  draught  and  the  violence 
of  the  repeated  shocks  to  which  vehicles  are  subjected  upon 
these  roads,  and  also  to  render  its  surface  practicable  for 
draught  animals,  it  is  customary  to  level  up  between  the 
logs  with  smaller  pieces  of  the  same  length  but  split  to  a 
triangular  cross-section.  These  are  inserted  with  edges 
downward,  in  the  open  joints,  so  as  to  bring  their  top  surfaces 
even  with  the  upper  sides  of  the  large  logs,  or  as  nearly  so 
as  practicable.  Upon  the  bed  thus  prepared  a layer  of  brush- 
wood is  put*,  with  a few  inches  in  thickness  of  soil  or  turf  on 


80 


ROADS,  STREETS,  AKD  PAVEMENTS. 


top  to  keep  it  in  place.  This  completes  the  road.  The 
logs  are  laid  directly  upon  the  natural  surface  of  the  soil, 
those  of  the  same  or  nearly  the  same  diameter  being  kept 
together,  and  the  top  covering  of  soil  is  excavated  from  side- 
ditches.  Cross  drains  may  usually  be  omitted  in  roads  of 
this  kind,  as  the  openings  between  the  logs,  even  when  laid 
with  the  utmost  care,  will  furnish  more  than  ample  water- 
way, for  drainage  from  the  ditch  on  the  upper  to  that  on  the 
lower  side  of  the  road.  When  the  passage  of  creeks  of  con- 
siderable volume  is  to  be  provided  for,  and  in  localities 
subjected  to  freshets,  cross-drains  or  culverts  are  made 
wherever  necessary  by  the  omission  of  two  or  more  logs,  the 
openings  being  bridged  with  planks,  split  rails  or  poles  laid 
transversely  to  the  axis  of  the  road,  and  resting  on  cross 
beams  notched  into  the  logs  on  either  side. 

Plank  Roads. 

Planlc  roads  were  much  in  vogue  twenty-five  to  thirty 
years  ago,  and  are  still  used  in  localities  where  lumber  is 
cheap,  and  stone  and  gravel  scarce  and  expensive.  They  are 
usually  about  8 feet  wide,  and  occupy  one  side  of  an  ordinary 
well-drained  and  properly  graded  earth  road,  the  other  side 
being  used  to  turn  out  upon,  and  for  travel  during  the  dry 
season.  The  method  of  construction  most  commonly  fol- 
lowed, is  to  lay  down  lengthwise  of  the  road,  two  parallel 
rows  of  plank  called  sleepers  or  stringers , about  5 feet  apart 
between  centres,  and  upon  these  to  lay  cross-planks  of  3 to 
4 inches  in  thickness,  and  8 feet  long,  so  adjusted  that  their 
ends  shall  not  be  in  a line  but  form  short  offsets  at  intervals 
of  2 to  3 feet,  to  prevent  the  formation  of  long  ruts  at  the 
edges  of  the  road,  and  aid  vehicles  in  regaining  the  plank 


GRAVEL  ROADS. 


81 


covering  from  the  earth  turn-out.  New  plank  roads  possess 
many  advantages,  for  heavy  haulage  as  well  as  for  light 
travel,  when  the  earth  road  is  muddy  and  soft,  but  in  a 
short  time  the  planks  become  so  worn  and  warped,  and  so 
many  of  them  get  displaced,  that  they  are  very  disagreeable 
loads  to  travel  upon.  They  are  so  deficient  in  durability 
that  a common  gravel  road,  as  hereinafter  described,  will 
in  the  end  be  found  more  profitable  in  most  localities.  The 
ease  and  rapidity  with  which  they  can  be  constructed  ren- 
ders them  a popular  and  even  a desirable  make-shift  in 
newly-settled  districts  and  towns  where  lumber  can  be  pro- 
cured at  low  cost,  but  they  lack  the  essential  features  of  per- 
manence and  durability  which  all  important  highways  should 
possess.  The  sleepers  ought  always  to  be  treated  by  some 
effective  wood-preserving  process  to  prevent  decay.  In  the 
planks,  ordinary  rot  will  be  anticipated  by  their  destruction 
from  wear  and  tear. 

Gravel  Roads. 

A capital  distinction  must  be  made  between  gravel  that 
will  pack  under  travel,  and  clean  rounded  gravel  which  will 
not , due  to  a small  proportion  of  clayey  or  earthy  matter 
contained  in  the  former,  which  unites  and  binds  the  materia] 
together.  Sea-side  and  river-side  gravel,  consisting  almost 
entirely  of  water- worn  and  rounded  pebbles  of  all  sizes, 
which  easily  move  and  slide  upon  each  other,  is  unsuitable 
for  a road-covering,  unless  other  materials  be  mixed  with  it, 
while  pit  gravel  generally  contains  too  much  earthy  matter. 
The  gravel  for  the  top  layer  at  least,  should  be  hard  and 
tough,  so  that  the  wear  will  not  pulverize  it  and  convert  it 
into  dust  and  mud.  It  should  be  coarse,  varying  in  size  from 


82 


ROADS,  STREETS,  AND  PAVEMENTS. 


half  an  inch  to  an  inch  and  a half  in  largest  dimensions.  It 
should  not  be  water-worn,  and  should  contain  enough  sandy 
and  clayey  loam  to  bind  it  together  firmly. 

Screening  the  Gravel. 

Pit  gravel  usually  contains  so  much  earthy  material  that 
it  should  be  screened,  to  render  it  entirely  suitable  for  the 
surface  layer.  For  this  purpose  two  wire  screens  will  be  nec- 
essary, one  with  the  wires  1|  to  If  inches  apart,  while  in  the 
other  they  should  not  be  more  than  ^ to  f inch  apart.  The 
pebbles  which  do  not  pass  the  large  screen  are  to  be  rejected, 
or  if  used,  are  broken  up  into  smaller  fragments ; while  the 
earth,  small  gravel,  and  sand  that  pass  the  smaller  one, 
although  unsuitable  for  the  road  surface,  will  answer  for  a 
sub-layer  or  bed  for  the  road  material  to  rest  upon,  or  for 
side-walk  coverings. 

If  the  bed  of  the  road  is  rock,  a layer  of  earth  should  be 
interposed  between  it  and  the  gravel,  to  prevent  the  too 
rapid  wear  of  the  latter. 

Applying  the  Covering. 

In  ordinary  soils  an  excavation  to  the  depth  of  10  to  12 
inches,  and  of  the  required  width,  is  made  for  the  reception 
of  the  gravel.  The  surface  of  this  excavated  form,  called 
the  sub-grade,  may  be  made  level,  or  preferably,  it  may  be 
arranged  parallel  to  the  finished  road  surface  by  sloping  it 
from  the  centre  toward  the  sides.  A layer  4 inches  thick  of 
\ good  unscreened  pit  gravel  in  its  natural  state  is  first  spread 
upon  the  road  bed,  which  is  then  thrown  open  to  travel 
until  it  becomes  tolerably  well  consolidated.  The  gravel 
will  usually  be  carried  upon  the  road  in  wheel-barrows  or 


APPLYING  THE  COVERING. 


83 


carts,  and  adjusted  to  an  even  layer  with  rakes.  The  work 
may  be  hastened  by  using  a cylindrical  roller  2\  to  3 feet  in 
diameter,  and  5 to  6 feet  long,  weighing  1-J-  to  2 tons.  A 
better  design  is  to  have  two  such  cylinders  arranged  in  a 
frame  one  behind  the  other,  each  being  composed  of  two 
short  cylinders  2%  to  3 feet  in  length,  placed  abreast  upon 
the  same  axis.  For  compacting  the  bottom  layers,  and  for 
the  preliminary  consolidation  of  the  upper  layers,  a heavier 
roller  cannot  be  used.  A roller  weighing  from  5 to  7 tons 
and  upwards  may  be  used  advantageously  on  the  top  layer, 
and  if  the  light  roller  is  not  so  constructed  as  to  admit  of 
loading,  it  would  be  well  to  have  two. 

The  heavy  roller  constructed  for  the  New  York  City  De- 
partment of  Parks,  weighed  six  and  a half  tons,  and  could 
be  loaded  up  to  twelve  tons.  “ It  was  composed  of  two  hol- 
low cylinders  of  cast  iron,  set  abreast  on  a strong  wrought- 
iron  axle,  making  together  a length  of  five  feet,  with  a diam- 
eter of  seven  feet.”  The  cylinders  were  set  in  a timber  frame- 
work, and  had  apertures  in  the  ends  through  which  broken 
stone  and  gravel  could  be  introduced  into  interior  compart- 
ments, by  means  of  which  the  aggregate  weight  could  be 
increased  to  twelve  tons.  This  roller  is  shown  in  Fig.  34, 
most  of  the  shafts  being  omitted  for  want  of  space. 

For  making  gravel  roads  a roller  weighing  6 tons  will 
suffice,  the  12  ton  roller  being  well  adapted  to  the  construc- 
tion of  broken  stone  or  Macadam  roads. 

A horse  road-roller  designed  and  used  in  Germany  is  so 
arranged  that  the  cylinder  can  be  filled  with  water,  when 
heavy  rolling  is  to  be  done.  When  not  in  use,  or  when 
about  to  move  from  place  to  place  the  water  is  emptied  out, 
and  the  weight  materially  lessened.  A full  description  of 


84 


ROADS,  STREETS,  AND  PAVEMENTS. 


this  roller  will  be  found  in  Mr.  Clemens  Herschel’s  “Trea- 
tise on  the  Science  of  Road-making,”  published  with  the 
executive  reports  of  the  Commonwealth  of  Massachusetts  for 
the  years  1869-?70.  Road-rollers  propelled  by  steam  power 
have  been  used  to  some  extent,  but  no  description  of  them 
is  deemed  necessary  here. 

During  the  consolidation  of  the  first  layer  by  the  light 
roller  and  by  the  traffic  over  it,  men  with  rakes  should  be 
kept  engaged  in  filling  up  the  ruts  as  fast  as  they  are  formed. 


Fig.  34. 


When  the  bottom  layer  is  tolerably  well,  though  not  thor 
oughly  compacted,  a second  layer  of  3 to  4 inches  is  added 
and  treated  in  the  same  manner.  Successive  layers  follow 
until  the  road  is  made  up  to  the  required  height  and  form 
of  transverse  section.  The  aggregate  thickness  of  the  sev- 
eral layers  need  not  exceed  10  to  12  inches. 

If  the  gravel  be  too  dry  to  consolidate  promptly  it  should 
be  kept  moist  by  sprinkling-carts,  care  being  taken  not  to 
make  it  so  wet  that  the  earthy  material  will  become  semi- 
fluid and  collect  on  the  surface. 


GRAVEL  ROADS. 


85 


If  the  screened  gravel  of  the  top  layer  is  so  deficient  in 
binding  material  that  it  will  not  pack  firmly  under  the  ordi- 
nary traffic  on  wheels,  a thin  layer,  not  exceeding  one  inch 
in  depth,  of  sandy  and  gravelly  loam  and  clay,  or  indurated 
sand  and  clay  known  as  hard  pan,  or  the  scrapings  from 
stone  yards,  should  he  spread  over  it  and  slightly  moistened 
by  sprinkling-carts  before  the  rolling  is  begun,  the  light 
roller  being  invariably  used  first.  A better  practice  would 
be  to  thoroughly  mix  the  binding  material  with  the  gravel 
for  the  top  layer  before  it  is  spread  upon  the  road. 

The  sides  of  the  road  should  be  rolled  first,  to  such 
degree  of  firmness  that  when  the  roller  is  placed  upon  the 
highest  portion  along  the  middle,  the  tendency  of  the  gravel 
to  spread  and  work  off  toward  the  side-gutters  will  be  resisted. 
During  the  consolidation  of  the  top  layer  the  material  must 
be  kept  properly  moistened,  and  men  with  rakes  should  be 
in  constant  attendance  to  fill  in  ruts  anu  depressions  so  as 
to  give  the  surface  the  required  form,  and  secure  uniform 
density  in  the  road-covering.  When  finished,  the  light  coab 
ing  of  binding  material  will  have  been  forced  down  several 
inches  into  the  top  layer,  forming  a kind  of  matrix  which 
holds  the  gravel  firmly  in  place,  and  provides  a nearly  water- 
tight covering  for  the  road  bed.  Gravel  beds  generally  con- 
tain a greater  or  less  quantity  of  large  rounded  pebbles,  of 
5 to  8 inches  in  longest  dimension,  which  if  not  broken  up 
into  small  fragments  and  incorporated  with  the  road-cover- 
ing, may  be  advantageously  employed  instead  of  sods,  for 
facing  the  inner  edge  of  the  foot-path  to  protect  it  from  the 
wash  of  the  side  gutters,  and  in  forming  the  small  drain 
under  the  foot-path  from  the  gutter  to  the  side-ditch. 


80  ROADS,  STREETS,  AND  PAVEMENTS. 

Good  Gravel  Roads. 

A gravel  road  carefully  constructed  in  the  manner  above 
described,  upon  soil  of  such  sandy  or  gravelly  character  that 
the  side-ditches  will  thoroughly  drain  the  road  bed  to  a 
depth  at  least  12  to  15  inches  below  the  bottom  of  the  road- 
covering, thereby  rendering  cross  drains  unnecessary,  will 
possess  all  the  essential  requisites  of  a good  road.  In  soils 
where  the  side-ditches  will  not  secure  good  sub-drainage, 
cross-drains,  which  cost  but  little,  should  be  introduced  under 
the  road  covering  at  suitable  intervals. 

Inferior  Gravel  Roads. 

Country  roads  made  with  gravel  are  too  frequently  of  a 
very  inferior  kind,  being  formed  either  by  simply  carting 
pit-gravel  upon  the  road,  and  dumping  it  into  the  ruts  and 
wheel  tracks,  and  the  gutter-like  depressions  worn  by  the 
tread  of  the  animals,  until  the  middle  of  the  roadway  grad- 
ually becomes  covered  to  a width  of  8 to  8£  feet,  and  a depth 
varying  from  3 to  4 inches  in  the  centre  and  6 to  10  inches 
under  the  wheels,  or  by  constructing  an  ordinary  earth  road 
with  a single  top  layer  of  gravel  4 to  6 inches  deep  and  8 to 
9 feet  wide  along  the  centre,  the  sides  or  wings  being 
finished  out  with  ordinary  soil.  . Wheel  ruts  will  form  rap- 
idly on  such  a road,  which  should  be  promptly  filled  with 
gravel.  By  this  means  the  thickness  of  the  gravel- covering 
will  be  gradually  increased  under  the  wheels  to  8 and  10  inches 
and  upward. 

Macadam  Roads. 

Macadam  roads,  Pig.  35,  are  constructed  with  successive 
layers  of  broken  stone,  applied  in  a manner  similar  to  that 


MACADAM  ROADS. 


87 


above  described  for  gravel  roads.  If  the  best  quality  of 
stone  cannot  be  procured  for  the  whole  of  the  road  covering, 
care  should  be  taken  to  select  the  hardest  and  toughest 
stone  for  the  upper,  or  preferably  for  the  two  upper  layers, 
having  an  aggregate  thickness  of  about  6 inches.  The  stone 
should  be  broken  into  fragments  as  nearly  cubical  in  form 
as  possible,  the  largest  of  which  should  not  exceed  2-J-  inches 
in  longest  diagonal  dimensions.  For  inspecting  the  broken 
stone,  an  iron  ring  2%  inches  in  diameter  may  be  used  with 
advantage. 


If  the  material  be  very  tough  and  hard,  like  most  of  the 
basaltic  and  trap  rocks  and  the  sienitic  granites,  or  if  the  traf- 
fic upon  the  road  be  light  and  its  amount  not  large,  the  stone 


Fig.  35. 


may  be  broken  smaller,  without  danger  of  their  crushing 
coo  easily  or  wearing  too  rapidly.  The  smaller  the  fragments, 
the  less  will  be  the  volume  of  voids  in  the  road  covering 
liable  to  become  filled  with  water  and  mud,  and  the  sooner 
will  the  surface  become  hard  and  smooth  when  opened  to 
traffic,  or  while  being  compacted  with  rollers. 

In  MacadanTs  matured  practice  upon  the  Bath  and 
Bristol  roads,  England,  he  did  not  allow  any  stone  above 
three  ounces  in  weight  (equal,  with  the  material  he  had,  to 
cubes  of  1^  inches  or  2 inches  in  their  longest  diagonal 
length);  to  be  used.  He  caused  splinters  and  thin  slices  and 
spalls  to  be  excluded  as  far  as  possible,  and  laid  considerable 


88 


ROADS,  STREETS,  AND  PAVEMENTS. 


stress  upon  uniformity  of  size,  and  perfect  cleanliness  or 
freedom  from  dust,  sand,  or  earthy  matter.  The  French 
engineers,  on  the  contrary,  are  indifferent  as  to  cleanliness, 
and  upon  their  broken  stone  roads  make  use  of  all  sizes  from 
the  dust  and  detritus  produced  in  breaking,  up  to  lj  inch 
cubes,  upon  the  assumption  that  the  smaller  particles  occupy 
only  a portion  of  the  original  void  space  between  the  larger 
fragments,  the  whole  of  which  will  sooner  or  later  become 
entirely  filled  with  dust  and  mud  ; an  assertion  which  must 
be  accepted  in  a modified  sense,  for  it  is  certain  that  a well 
constructed  and  properly  maintained  Macadam  road  should 
allow,  and  will  allow  all  surface  water  which  finds  its  way 
through  the  crust  of  the  road  surface,  to  percolate  freely 
through  to  the  bottom  of  broken  stone  covering,  where  its 
prompt  escape  is  provided  for  by  suitable  sub-drainage,  upon 
soils  where  such  a precaution  is  necessary. 

The  stone,  if  broken  by  hand  hammers,  will  comprise 
fragments  of  all  sizes,  from  the  largest  allowable  dimensions, 
down  to  small  particles  and  dust,  and  of  various  angular, 
prismoidal,  and  cubical  forms. 

It  is  not  customary  or  necessary  to  screen  hand-broken 
stone,  but  in  loading  it  into  the  barrows  or  carts  for  trans- 
portation to  the  road,  the  detritus  and  most  of  the  finer 
particles  maybe  left  behind  by  using  the  broad  forks  already 
described.  (Fig.  32.)  If  the  prevailing  forms  are  angular, 
and  of  all  sizes  below  the  maximum  prescribed,  the  fragments 
will  unite  and  dovetail  together  more  firmly  and  compactly 
than  cubes,  and  very  little  if  any  binding  material  is  neces- 
sary. If  the  smaller  fragments  and  detritus  be  carefully 
excluded  by  screening,  the  road  cannot  be  compacted  into  a 
smooth  hard  surface  by  rolling  or  by  traffic. 


MACADAM  IlOADS  1M  CDNTHAL  PAKK. 


89 


Mr.Wm.  H.  Grant,  Superintending  Engineer  of  the  New 
Vork  Central  Park,  in  his  report  upon  the  park  roads,  says, 
“ At  the  commencement  of  the  Macadam  roads,  the  experi- 
ment was  tried  of  rolling  and  compacting  the  stone  by  a 
strict  adherence  to  Macadam’s  theory — that  of  carefully 
excluding  all  dirt  and  foreign  material  from  the  stones,  and 
trusting  to  the  action  of  the  roller  and  the  travel  of  teams 
to  accomplish  the  work  of  consolidation.  The  bottom 
layer  of  stone  was  sufficiently  compacted  in  this  way  to  form 
and  retain,  under  the  action  of  the  rollers,  (after  the  com- 
pression had  reached  about  its  practical  limit)  an  even  and 
regular  surface,  but  the  top  layer — with  the  use  of  the  heavy 
roller  loaded  to  its  greatest  capacity — it  was  found  impracti- 
cable to  solidify  and  reduce  to  such  a surface  as  would  pre- 
vent the  stones  from  loosening  and  being  displaced  by  the 
action  of  wagon  wheels  and  horses’  feet.  No  amount  of 
rolling  was  sufficient  to  produce  a thorough  binding  effect 
upon  the  stones,  or  to  cause  such  a mechanical  union  and 
adjustment  of  their  sides  and  angles  together  as  to  enable 
them  mutually  to  assist  each  other  in  resisting  displacement. 
The  rolling  was  persisted  in,  with  the  roller  adjusted  to  dif- 
ferent weights  up  to  the  maximum  load,”  (12  tons)  “ until 
it  was  apparent  that  the  opposite  effect  from  that  intended 
was  being  produced.  The  stones  became  rounded  by  the 
excessive  attrition  they  were  subjected  to,  their  more  angular 
parts  wearing  away,  and  the  weaker  and  smaller  ones  being 
crushed.  The  experiment  was  not  pushed  beyond  this 
point.  It  was  conclusively  shown,  that  broken  stones  of 
the  ordinary  sizes,  and  of  the  very  best  quality  for  wear  and 
durability,  with  the  greatest  care  and  attention  to  all  the 
necessary  conditions  of  rolling  and  compression,  would  not 


90 


ROADS,  STREETS,  AND  PAVEMENTS. 


consolidate  in  the  effectual  manner  required  for  the  surface 
of  a road,  while  entirely  isolated  from,  and  independent  of 
other  substances.  The  utmost  efforts  to  compress  and 
solidify  them  while  in  this  condition,  after  a certain  limit 
had  been  reached,  were  unavailing/*5 

Examination  and  Tests  of  the  Stone. 

In  order  to  decide  upon  the  fitness  of  any  particular 
kind  of  stone  for  road  covering,  and  especially  when  there 
are  several  kinds  equally  available,  or  so  nearly  so  that  the 
question  of  selection  should  be  governed  by  the  quality 
alone,  an  examination  and  tests  of  the  varieties  should  be 
made,  in  order  to  determine  their  relative  toughness,  hard- 
ness, and  power  to  resist  abrasion.  In  some  cases  the  dif- 
ference of  quality  is  so  pronounced  and  so  well  known,  that 
the  opinion  of  intelligent  stone-cutters  of  the  neighborhood, 
who  have  been  accustomed  to  work  the  several  kinds  of 
stone  into  various  forms  with  different  tools,  will  be  suffi- 
cient to  indicate  their  order,  though  not  their  degrees  of 
merit,  for  the  purposes  in  view.  When,  however,  the  infor- 
mation thus  obtained  is  deemed  inadequate  or  inconclusive, 
the  examination  may  be  continued  as  follows  : 

First . Average  samples  of  the  several  stones — say  a ton 
of  each — should  be  collected  together,  and  placed  in  separate 
piles  in  some  convenient  place.  A practical  stone-breaker 
should  then  be  set  to  work  with  the  ordinary  stone  hand- 
hammer,  with  directions  to  break  up  the  material  into 
sizes  suitable  for  road  metal,  devoting  an  hour  to  each  pile 
alternately,  under  the  constant  observation  of  the  individual 
conducting  the  investigation.  By  this  means  the  order  of 
toughness  of  the  several  kinds  of  stone  under  examination 


TESTING  THE  STOKE. 


91 

will  be  ascertained,  for  it  is  the  toughness,  especially  when 
in  small  fragments,  which  enables  a stone  to  resist  frac 
tu  re  from  the  repeated  blows  of  a blunt  tool  harder  than 
itself. 

Second . The  power  to  resist  abrasion,  or  at  least  the 
order  of  quality  in  this  respect  of  the  several  kinds  of  stone 
under  trial,  may  be  ascertained  by  grinding  them  under 
equal  pressure,  upon  an  ordinary  grindstone  run  by  power 
at  a uniform  speed.  For  this  purpose  bars  of  the  same  size, 
about  2-in.  by  2-in.  by  6-in.  should  be  prepared  from  each 
sample  under  trial,  in  some  of  which  the  laminae  should 
be  parallel  to  the  end  of  the  block,  and  in  others  perpendicu- 
lar thereto.  The  blocks  are  then  tested  one  after  the  other, 
by  putting  them  endwise  in  a long  box  open  at  the  lower 
end  and  closed  at  top,  arranged  vertically  over  the  grind- 
stone, with  its  lower  end  nearly  touching  the  grinding  sur- 
face. The  box  is  firmly  held  in  this  position  by  framework 
attached  to  the  grindstone  frame.  In  the  upper  end  of  the 
box,  directly  above  the  specimen,  there  is  placed  a spiral 
spring,  which  is  strongly  compressed  upwards  against  the 
top  of  the  box,  by  the  insertion  of  the  stone  specimen  from 
the  lower  or  open  end.  This  spring  supplies  the  force  which 
presses  the  lower  end  of  the  specimen  against  the  grinding 
surface,  and  of  course  exerts  an  equal  force  upon  blocks  of 
equal  length.  The  amounts  ground  in  equal  times  from  the 
several  blocks,  as  determined  by  their  lessened  weight,  will 
give  the  inverse  order  of  their  powers  to  resist  abrasion. 

Third.  The  compressive  strength  of  the  stones  in  small 
(say  2-inch)  cubes,  although  less  directly  indicative  of 
their  fitness  for  road  covering  than  the  foregoing  tests, 
should  also  be  ascertained,  when  it  is  convenient  to  do  so,  ae 


^2  ROADS,  STREETS,  AtfD  PAVEMENTS. 

corroborative  data.  With  the  information  thus  obtained  it 
will  not  be  difficult  to  make  a judicious  selection. 

Stone-Crusher. 

Blake’s  stone-crusher,  of  which  a longitudinal  section  and 
a perspective  view  of  the  essential  parts  is  shown  in  Figs. 
36  and  37,  is  an  excellent  machine  for  breaking  stone  foi 
concrete  or  for  road-coverings.  A A is  a frame  of  cast  iron 


Fig.  36. 


in  one  piece,  which  supports  the  other  parts.  It  consists 
of  two  parallel  cheeks  shaded  dark  in  the  drawing,  connected 
together  by  the  parts  A A.  B represents  a fly  wheel  work- 
ing on  a shaft  having  its  bearings  at  D,  and  formed  into  a 
crank  between  the  bearings.  It  carries  a pulley  C,  which 
receives  a belt  from  a steam  engine.  F is  a rod  or  pitman 
connecting  the  crank  with  the  toggles  CHx.  The  end  of 
the  frame  A,  on  the  right  of  the  figure,  supports  a fixed 
jaw  H against  which  the  stones  are  crushed.  J is  the  movable 


BLAKE  S STOHE-OKUSHER. 


93 


jaw  pivoted  at  K.  L is  a spring  of  India  rubber  which 
being  compressed  at  each  forward  movement  of  the  jaw  J, 
aids  its  return.  Every  revolution  of  the  crank  causes  the 
pitman  P to  rise  and  fall,  and  the  movable  jaw  to  advance 
a short  distance  toward  the  fixed  jaw  and  return,  so  that  a 
stone  dropped  in  between  the  jaws  J and  H,  will  be  broken 


Fig.  37. 


at  the  next  succeeding-  bite.  The  fragments  will  then  fall 
lower  down  and  be  broken  again  and  again  at  each  revolu- 
tion until  they  pass  out  at  the  bottom.  The  bottom  of  the 
opening  between  the  jaws  may  be  set  so  as  to  deliver  any 
required  size  of  broken  stone,  by  suitably  adjusting  the  wedge 
N,  inserted  against  the  toggle  block  O.  The  crushed  stone 
passes  from  the  machine  directly  into  a revolving  cylindrical 
screen,  inclined  to  the  horizon,  the  meshes  of  which  are 


94 


ROADS,  STREETS,  AND  PAVEMENTS. 


small  at  the  upper  end,  and  of  medium  size,  or  about  2%  t<r 
2£  inches  square  in  the  middle  and  lower  portion.  The  dust 
and  small  particles  pass  through  the  meshes  in  the  uppei 
end,  while  the  large  fragments  which  issue  out  of  the  lower 
end  of  the  cylinder,  are  returned  to  the  machine  to  be 
broken  again.  The  rest  is  suitable  for  road-covering  with- 
out any  further  preparation.  The  proper  speed  of  these 
machines  is  about  200  revolutions  of  the  crank  per  minute. 
They  are  made  of  several  sizes,  requiring  engines  of  4 to  12 
horse  power,  and  their  working  capacity  varies  correspond- 
ingly from  3 to  7 cubic  yards  of  broken  stone  per  hour.  The 
best  size  for  breaking  road  material  is  one  having  a capacity 
to  receive  stones  8 to  9 inches  thick  and  14  to  15  inches  wide. 

Thickness  of  the  Road-covering. 

The  thickness  of  the  covering  need  not  exceed  10  or  11 
inches  of  well  consolidated  materials  on  a good  road  bed,  for 
roads  in  cold  climates  subjected  to  the  heaviest  traffic.  The 
French  road  engineers  consider  ten  inches  sufficient  in 
France,  upon  the  most  important  roads,  and  6,  7,  and  8 
inches  where  the  traffic  is  comparatively  light.  Macadam 
considered  10  inches  of  well  compacted  materials  enough 
for  very  heavy  traffic,  and  generally  advocates  less  thickness 
than  most  English  constructors.  Six  inches  for  the  mini- 
mum and  ten  for  the  maximum  thickness  appear  to  have 
been  his  limits.  In  one  instance  he  speaks  of  a road  which 
“having  been  allowed  to  wear  down  to  only  three  inches, 
this  was  found  sufficient  to  prevent  the  water  from  pene- 
trating, and  thus  to  escape  any  injury  from  frost,”  and  in 
another,  states  that  “ some  new  roads  of  six  inches  in  depth 
were  not  at  all  affected  by  a very  severe  winter.” 


APPLYING  TIIE  MATERIAL. 


95 


Applying  the  Road-covering. 

The  drainage  of  the  road  bed  having  been  provided  for 
by  side-ditches,  and  if  necessary  by  suitable  cross-drains,  an 
excavation  is  then  made  to  the  sub-grade  for  the  reception 
of  the  road  materials,  sloping  from  the  middle  toward  the 
sides  the  same  as  the  finished  road  surface,  the  depth  of 
the  excavation  being  regulated  by  the  thickness  adopted  for 
the  covering.  It  would  be  well,  especially  in  made  ground 
to  consolidate  the  bed  by  rollers,  or  by  ramming. 

A layer  of  broken  stone  three  inches  in  thickness  is  then 
applied,  care  being  taken,  if  dumped  from  carts  or  barrows, 
to  spread  it  evenly  with  a rake.  The  road  is  then  opened  to 
travel  in  order  that  it  may  be  compacted  before  the  addition 
of  more  stone.  This  operation  may  be  greatly  hastened  by 
rolling,  beginning  with  the  light  and  ending  with  the  heavy 
roller.  If  the  road  bed  be  soft  and  yielding,  whether  natu- 
rally so  at  all  times,  or  exceptionally  so  from  recent  rains,  it 
may  be  necessary  to  omit  using  the  heavy  roller,  for  fear  of 
forcing  the  bottom  stone  down  into  the  soil. 

Euts  must  be  carefully  raked  in  as  fast  as  they  are  formed. 
Experience  has  demonstrated  that  3,  or  at  most  4 inches  of 
broken  stone,  is  the  greatest  thickness  that  can  be  well  com- 
pacted at  one  time. 

The  “Wings”  of  Country  Roads. 

As  it  will  seldom  be  necessary,  except  near  large  towns 
and  cities,  to  apply  the  broken  stone  over  a greater  width 
than  16  feet,  pit  gravel,  or  sandy  or  gravelly  earth  may  be 
used  for  extending  the  layer  over  the  cc  wings.  ’ This  should 
Oe  laid  on  and  consolidated  at  the  same  time  with  the  broken 


96 


ROADS,  STREETS,  AND  PAVEMENTS. 


stone.  When  the  lower  layer  shall  have  attained  an  even 
and  tolerably  well  compacted  surface,  a second  layer  of  stone 
not  exceeding  3 inches  in  thickness,  with  gravel  or  earth  on 
the  wings,  is  then  applied,  and  compacted  by  traffic  and  by 
rolling  as  before.  The  top  layer  is  spread  and  consolidated 
in  the  same  manner,  but  here  the  process  of  rolling  should 
be  prolonged,  and  an  ample  force  of  men  should  be  kept  con, 
stantly  employed  in  filling  in  the  ruts,  and  in  removing 
lumps  and  elevations,  so  that  the  finished  surface  shall  not 
only  be  hard  and  smooth,  but  accurately  adjusted  to  the 
required  gradients  and  transverse  form.  The  roller  should 
pass  over  every  portion  of  the  road  surface  from  40  to  60,  or 
if  necessary,  even  100  times,  and  if  the  weather  be  dry  the 
materials  -should  be  kept  damp  by  sprinkling  carts.  A bind- 
ing layer  about  1 inch  in  thickness  of  gravel,  or  gravelly 
earth  or  hard  pan,  may  be  spread  upon  the  top  layer  after  it 
has  become  nearly  consolidated,  unless  the  character  of  the 
broken  stone  is  such  as  to  render  this  precaution  unnecessary. 
When  thoroughly  consolidated,  the  finished  road  surface  will 
not  show  any  tendency  to  rise  up  and  form  a ridge  in  front 
of  a 9 ton  or  10  ton  roller. 

Telford  Roads. 

These  roads — named  after  Thomas  Telford,  by  whom 
hey  were  first  constructed  in  Great  Britain — are  made  with 
payers  of  broken  stone  resting  upon  a sub-pavement  of  stone 
blojks.  Fig.  33  shows  a transverse  half-section  of  a road  30 
feet  wide,  with  a Telford  covering  16  feet  wide  along  the 
m c1  die,  and  gravel  wifigs. 

Telford’s  specifications  for  a roadway  30  feet  wide  were 
as  follows  : “ Upon  a level  bed  prepared  for  the  road  mate- 


TELFORD  ROADS. 


9? 


rials  a boiforr  course  or  layer  of  stones  is  to  be  set  by  hand 
in  the  form  of  « close,  firm  pavement.  The  stones  set  in 
the  middle  of  tut,  road  are  to  be  seven  inches  in  depth ; at 
nine  feet  from  the  centre,  five  inches  ; at  twelve  from  the 
centre,  four  inches  ; and  at  fifteen  feet,  three  inches.  They 
are  to  be  set  on  their  broadest  edges  and  lengthivise  across  the 
road , and  the  breadth  of  the  upper  edge  is  not  to  exceed 
eour  inches  in  any  case.  Adi  the  irregularities  of  the  upper 
part  of  the  said  pavement  are  to  be  broken  off  by  the  ham- 
mer, and  all  the  interstices  are  to  be  filled  with  stone  chips, 
firmly  wedged  or  packed  by  hand  with  a ligh.  hammer, 
so  that  when  the  whole  pavement  is  finished,  there  shall  be 
a convexity  of  four  inches  in  the  breadth  of  fifteen  feet  frem 
the  centre. 

“The  middle  eighteen  feet  of  pavement  is  to  be  coated 
with  hard  stones  to  the  depth  of  six  inches.  Four  of  these 

six  inches  are  to  be  first  put  on  and  worked  in  by  carriages 

% 

and  horses,  care  being  taken  to  rake  in  the  ruts  until  the 
surface  becomes  firm  and  consolidated,  after  which  the 
remaining  two  inches  are  to  be  put  on.  The  whole  of  this 
stone  is  to  be  broken  into  pieces  as  nearly  cubical  as  possible, 
so  that  the  largest  piece,  in  its  longest  dimensions,  may  pass 
through  a ring  of  two  inches  and  a half  inside  diameter. 

“The  paved  spaces  on  each  side  of  the  eighteen  middle 
feet,  are  to  be  coated  with  broken  stones,  or  well  cleansed 
strong  gravel,  up  to  the  footpath  or  other  boundary  of  the 
road,  so  as  to  make  the  whole  convexity  of  the  road  six 
inches  from  the  centre  to  the  sides  of  it.  The  whole  of  the 
materials  are  to  be  covered  with  a binding  of  an  inch  and  a 
half  in  depth  of  good  gravel,  free  from  clay  or  earth.” 


ROADS,  STREETS,  AND  PAVEMENTS. 


98 

The  Telford  Sub-pavement. 

For  the  sub-pavement  the  stone  may  be  of  inferior 
quality,  as  it  is  not  subjected  to  severe  wear  and  tear ; but 
the  toughest  and  hardest  materials  should  be  used  for  the 
top  layer  of  broken  stone. 

The  only  advantage  gained  by  setting  the  sub-pavement 
on  a level  bed,  and  gaining  the  required  convexity  of  cross 
section  by  placing  the  deeper  stones  in  the  middle  of  the 
roadway,  is  a saving  of  expense  in  allowing  the  use  of  small 
stones  at  the  sides.  A better  drainage  of  the  road  bed 
would  doubtless  be  secured  by  making  it  parallel  to  the 
finished  road  surface,  as  was  done  with  the  Telford  roads 
constructed  in  the  New  York  Central  Park. 

The  advantages  and  disadvantages  of  the  sub-pavement 
or  “ bottoming, ” which  forms  the  characteristic  difference 
between  the  Telford  and  the  Macadam  roads,  have  been  the 
subject  of  lengthy  discussion  between  the  advocates  of  these 
two  methods  of  road  construction. 

It  is  alleged  against  the  Macadam  roads,  that  in  com- 
pressible soils  like  clay,  the  weight  of  loaded  wagons  forces 
the  stones  into  the  earth  ; that  in  wet  weather  the  clay  rises 
up  into  the  voids  between  the  stone  fragments,  and  prevents 
a thorough  consolidation  of  the  road  covering  ; that  in  high 
.atitudes  the  extreme  cold  of  winter  breaks  up  the  road  ; 
that  after  a thaw  the  surface  is  liable  to  be  cut  up  into 
Jeep  furrows  by  the  wheels  ; that  during  a drought  the  ordi- 
nary traffic  upon  the  road  causes  a constant  movement  and 
consequently  excessive  wear  among  the  broken  stones  ; that 
there  will  also  be  considerable  movement  and  therefore  weai 
and  tear  due  to  the  elasticity  of  the  road  bed,  which  cannot 


SUB- PAVEMENT  ROADS. 


99 

oe  entirely  prevented  by  any  ordinary  thickness  of  broken 
stone  alone  ; and  finally  that  the  Telford  bottoming  consti- 
tutes a thorough  underdrain,  and  besides  being  a remedy 
for  all  these  imputed  defects,  is  less  costly  than  its  equiva- 
lent of  broken  stone,  as  substituted  by  Macadam. 

On  the  other  hand,  it  is  claimed  by  the  partisans  of  the 
Macadam  system,  that  the  evils  complained  of  do  not  exist 
to  the  extent  alleged ; that  suitable  drainage  will  prevent 
them  entirely ; that  between  the  loaded  vehicles  above  and 
the  stone  pavement  below,  the  broken  stone  wears  away 
much  more  rapidly  than  if  laid  directly  on  the  earth ; and 
that  generally  a soft  and  elastic  bottom  is  superior  to  a hard 
and  unyielding  one. 

In  constructing  a road — whether  a Telford  or  a Macadam 
—upon  newly  embanked  earth,  or  any  light  soil  that  ha* 
not  become  thoroughly  compacted,  it  is  well  to  put  tha 
bottoming,  or  the  lower  course  of  broken  stone,  upon 
layer  of  brushwood  or  fascines,  in  order  that  the  settlement 
may  be  equalized  as  far  as  possible,  and  the  formation  oi 
deep  ruts  prevented. 

Rollers  for  compacting  the  road  bed,  before  the  bottoming 
is  put  down,  and  for  consolidating  the  layers  of  broken  stone, 
may  of  course  be  used  in  the  same  manner  and  with  equal 
advantages  upon  Telford  roads,  or  upon  those  where  the 
covering  is  broken  stone  only,  or  gravel  only. 

Telford  Sub-pavement,  with  Gravel  and 
broken  Stone  on  top. 

In  some  localities  there  may  be  an  abundance  of  stone, 
such  as  sandstone  and  the  softer  varieties  of  limestone  and 
gneiss,  which  is  entirely  suitable  for  the  Telford  bottoming 


100 


ROADS,  STREETS,  AND  PAVEMENTS. 


but  does  not  possess  the  requisite  hardness  and  toughness  for 
the  top  layer  of  broken  stone.  In  such  cases  after  the  bot- 
toming is  set,  the  road  may  be  finished  with  three  to  four 
inches  of  good  gravel  surmounted  by  a top  or  surface  layer 
of  good  broken  stone ; or,  the  broken  stone  if  too  costly, 
may  be  omitted  altogether,  and  the  surface  finished  with  a 
second  layer  of  good  gravel,  in  the  manner  described  for 
gravel  roads. 

Whenever  it  is  necessary  to  use  an  inferior  quality  of 
stone  for  the  sub-pavement,  the  method  of  gaining  the 
requisite  transverse  convexity  by  setting  the  smaller  stones 
on  the  wings  should  not  be  followed,  lest  the  road  covering 
should  fail  there  before  it  becomes  seriously  impaired  in  the 
middle.  This  precaution  is  specially  applicable  in  cases 
where  the  amount  of  traffic  is  so  great  that  the  entire  width 
of  the  road  is  used  more  or  less  constantly. 

Rubble-Stone  Sub-foundation  and  Telford 
Pavement. 

In  soft  ground  it  is  very  desirable  that  the  foundation 
should  possess  sufficient  firmness  and  unity  of  mass,  to  be 
able  to  resist  any  tendency  to  motion  among  the  stones  com- 
posing it,  caused  by  the  weight  of  passing  vehicles,  and  the 
working  up  of  the  underlying  soil  into  the  interstices  of  the 
road  covering.  In  order  to  secure  this  condition,  a layer 
composed  of  rubble  stones,  varying  in  thickness  from  3 to  5 
inches,  and  in  width  and  length  from  8 to  18  inches,  is  some- 
times placed  upon  the  road  bed  as  a foundation  for  the  Tel- 
ford sub-pavement.  The  stones  are  placed  close  together 
side  by  side  flatwise,  and  rammed  to  their  places,  the  inter- 
stices being  afterwards  filled  in  and  leveled  up  with  chips 


RUBBLE-STONE  FOUNDATIONS. 


10! 


and  spalls.  A thin  layer  of  sand  or  gravel  is  then  spread 
over  the  surface,  and  compacted  by  ramming  or  rolling. 
Upon  the  foundation  thus  prepared,  the  Telford  pavement  is 
set,  and  the  road  is  then  finished  with  broken  stone  or  gravel 
in  layers,  after  the  manner  already  described. 

Rubble-Stone  Foundation  without  the  Telford 
Pavement. 


When  the  foundation  is  of  rubble  stones  only,  Fig.  38,  it 
should,  if  the  material  is  not  too  costly,  have  a depth  of  not 
less  than  one-half  nor  more  than  two-thirds  of  the  entire 


thickness  of  the  road  covering,  whether  the  superstructure' 
be  of  broken  stone  or  gravel.  For  a total  thickness  of  10 
inches  of  road  covering,  the  rubble  foundation  may  be  from 
6 to  7 inches  thick,  while  7 to  8 inches  of  rubble  will  not  be 
too  much  for  a road  12  inches  thick. 

The  foundation  should  be  constructed  with  great  care, 
the  larger  stones  being  laid  down  first,  side  by  side,  flatwise 
upon  the  road  bed,  and  firmly  set  to  their  places  with 
rammers.  The  interstices  are  then  filled  in  and  leveled  up 
with  smaller  stones,  care  being  taken  by  selecting  the  pieces, 
to  get  them  to  fit  as  closely  together  as  possible,  and  thereby 
to  mutually  sustain  each  other  in  place.  The  object  is  to  use 
as  much  material  as  possible  in  a given  thickness,  so  as  to 
reduce  the  volume  of  voids  to  a minimum. 

In  placing  the  superstructure  the  first  layer,  whether  it 


102 


ROADS,  STREETS,  AND  PAVEMENTS. 


be  broken  stone  or  gravel,  should  not  exceed  2 inches  in 
thickness,  and  it  should  be  thoroughly  compacted  by  rollers 
and  by  traffic  before  another  is  applied,  in  order  that  it  may 
penetrate  and  unite  with  the  foundation,  and  become  indeed 
a part  of  it,  during  the  process  of  construction.  Otherwise 
there  will  be  a subsequent  tendency  to  work  down  into  the 
rubble  work  unequally,  causing  ruts  and  depressions  in  the 
road  surface.  Moreover,  it  is  of  great  importance  that 
the  foundation  itself  should  remain  firm  and  intact,  and  that 
the  least  motion  among  its  elementary  parts  should  be  avoided, 
lest  the  stones  should,  in  process  of  time,  work  up  to  the 
surface  and  destroy  the  road. 

Macadam  mentions  the  case  of  a road  on  Breslington  Com- 
mon, England,  in  the  construction  of  which  flag  stones  were 
laid  down  over  the  entire  road-bed,  and  the  road  covering 
laid  upon  them.  Their  constant  motion,  or  the  slight  tilt- 
ing up  of  one  end  whenever  a heavily  loaded  vehicle  passed 
over  the  other  end,  kept  the  surface  in  a loose  and  unsettled 
state.  Eventually  they  were  found  canted  up  and  standing 
on  their  edges,  and  it  was  necessary  to  reconstruct  the  road. 

Any  possible  motion  in  the  foundation  should  be  scrupu- 
lously guarded  against,  as  likely  to  prove  fatal  to  the  stabil- 
ity and  durability  of  the  road.  Where  there  is  any  reason  to 
apprehend  trouble  from  this  cause,  and  indeed  when  the 
closest  supervision  cannot  be  had  over  the  work,  it  will  be 
safer  to  set  the  stones  on  their  edge  as  nearly  as  possible  after 
Telford’s  method,  even  should  they  be  greatly  dissimilar  in 
size  and  shape,  for  an  opportunity  is  then  afforded  to  wedge 
in  between  them  with  chips  and  spalls,  so  as  to  guard  quite 
effectually  against  their  subsequent  displacement  from  the  ef- 
fects of  moving  loads.  The  stones  may  vary  in  thickness  from 


CONCRETE  FOUND ATIQNS. 


103 


3 to  6 inches,  in  width  or  depth  from  6 to  9 inches  along  the 
middle  of  the  road,  and  in  length  from  8 to  18  inches,  without 
rendering  it  difficult  to  form  them  systematically  into  a sub- 
pavement, greatly  superior  in  firmness  and  stability  to  any 
mere  rubble-work  foundation.  Even  flat  cobble  stones  can 
be  used,  mixed  in  with  the  irregular  fragments.  The  plan  of 
such  a foundation  is  shown  in  Fig.  40,  and  a vertical  section 
transversely  to  the  line  of  the  road  in  Fig.  39. 


Fig.  39. 


Concrete  Foundation  surmounted  with  Gravel 
or  broken  Stone. 

In  soft,  wet  and  elastic  soils,  liable  to  more  or  less  con- 
stant saturation  with  water,  and  especially  in  cuttings 
through  clay  banks,  and  in  other  localities  where  the  side 
slopes  are  badly  infested  with  springs,  the  difficulty  in  the 
way  of  securing  firmness  and  stability  in  the  road  foundation 
is  frequently  of  very  serious  character,  in  consequence  of 
imperfect  sub-drainage.  Parnell  instances  the  case  of  the 
Higligate  - Archway  Eoad,  near  London,  located  between 
banks  of  clay  where  the  soil  was  surcharged  with  water. 
Many  fruitless  attempts  to  drain  the  road  bed  had  been 
made,  a large  quantity  of  broken  stone  had  been  used  in  the 
first  instance,  and  subsequently  taken  up  and  relaid  on  gorse, 


104 


ROADS,  STREETS,  AND  PAVEMENTS. 


brush  and  pieces  of  refuse  tin.  It  was  found  impossible  to 
consolidate  the  broken  stone.  It  mixed  up  with  the  clay, 
and  rapidly  wore  round  and  smooth,  and  the  road  finally 
became  nearly  impassable.  It  was  rebuilt  under  the  direction 
of  Sir  John  MacNeill  in  the  following  manner  : A thorough 
system  of  sub-drainage  was  applied  by  making  four  longi- 
tudinal drains  throughout  the  entire  length  of  the  road, 
with  cross  drains  at  intervals  of  90  feet.  Smaller  drains  were 
placed  30  feet  apart.  On  the  road  bed  thus  prepared  to  a 
width  of  18  feet,  a foundation  of  concrete  6 inches  thick  was 
laid.  The  surface  of  the  concrete  was  indented  transversely 
by  a series  of  shallow  triangular  grooves,  formed  by  embed- 
ding strips  of  wood  in  the  concrete  before  it  had  set.  These 
grooves  were  about  4 inches  apart,  and  had  a fall  of  3 inches 
from  the  centre  of  the  road  to  the  sides,  in  order  that  any 
water  which  might  percolate  through  the  broken  stone  cov- 
ering, would  be  promptly  carried  off.  After  the  concrete 
had  set,  the  superstructure  consisting  of  six  inches  of  broken 
stone  was  laid  upon  it,  the  wings  or  sides  being  carried  out 
to  the  side  gutters  with  flint  gravel.  By  this  means  a dry 
and  firm  foundation  was  secured  for  the  broken  stone,  and 
all  possibility  of  any  displacement  of  the  latter  by  mixing  in 
with  the  clay  subsoil,  or  by  the  action  of  frost,  prevented. 
The  result,  as  might  have  been  expected,  was  a first  rate 
road.  The  concrete  used  for  the  foundation  was  composed 
of  1 part  of  Roman  cement,  and  1 part  of  sand  mixed 
together  dry.  Eight  parts  of  broken  stone  was  then  incor- 
porated, using  as  little  water  as  possible.  From  these  pro- 
portions it  is  evident  that  there  was  not  enough  mortar  in 
the  concrete  to  fill  the  voids  in  the  broken  stone,  while  there 
doubtless  was  sufficient  to  bind  the  ballast  together  firmly, 


BUBBLE-STONE  AND  CONCRETE. 


105 


and  resist  the  tendency  to  break  up  under  the  weight  of 
loaded  vehicles. 

Concrete  foundations,  even  if  laid  upon  a level  bed, 
should  be  finished  on  top  with  a slope  from  the  centre  to 
the  sides,  about  the  same  as  that  given  to  the  road  surface, 
to  facilitate  the  drainage  of  the  top  covering. 

Foundation  of  Rubble-stone  and  Concrete. 

Reference  has  been  made  to  the  difficulty  experienced  in 
wet  and  elastic  sub-soils  in  keeping  a foundation  of  rubble 
stones  firm  and  intact,  and  in  preventing  the  stones  working 
up  and  finally  destroying  the  road  surface.  A remedy  for 
this  evil  is  found  in  the  judicious  use  of  hydraulic  concrete 
between  the  stones,  as  shown*  in  Fig.  41.  In  founding  by 


Fig.  41. 


this  method,  the  largest  stones  and  those  most  nearly  ap* 
proaching  the  form  of  cubical  and  rectangular  blocks,  should 
be  laid  down  first,  side  by  side,  but  not  in  close  contact,  each 
stone  being  firmly  set  to  its  place  by  ramming.  Concrete, 
in  which  the  ballast  should  be  composed  of  stone  fragments 
not  exceeding  f inch  in  longest  dimension,  or  of  a mixture 
of  such  fragments  and  pebbles  of  all  sizes  up  to  f inch  diam- 
eter, is  well  tamped  in  between  and  around  the  stones  and 
carried  up  to  the  general  line  of  their  top  surfaces.  If  a 
thickness  of  6 to  8 inches  is  secured  in  this  manner  by  one 
course  of  stones,  this  will  suffice,  and  the  road  may  be  fin- 
ished in  the  usual  manner  with  layers  of  broken  stone  or 
gravel. 


5* 


) 0-0  ROADSy  STREETS,  AND  PAVEMENTS. 

A foundation  of  this  kind  is  believed  to  be  as  firm  and 
durable  as  one  of  the  same  thickness  composed  entirely  of 
concrete,  while  it  costs  considerably  less.  Its  top  surface 
should  slope  from  the  centre  to  the  sides,  in  order  to  carry 
off  all  the  water  which  percolates  through  the  top  layer  of 
stone  or  gravel,  a condition  which  can  be  secured  either  by 
sloping  the  road  bed,  or  by  selecting  the  larger  or  deeper 
stones  for  the  middle  and  gradually  decreasing  their  depth 
toward  the  sides,  thus  giving  a greater  thickness  of  founda- 
tion in  the  centre  than  at  the  sides. 

It  is  of  capital  importance,  in  a foundation  of  this  descrip- 
tion, that  the  stones  should  be  of  such  shapes  that  when  set 
in  place  their  side  surfaces  will  be  nearly  vertical,  or  rather 
will  be  as  nearly  perpendicular  to  the  road  surface  as  possi- 
ble, so  that  the  concrete,  after  setting,  will  hold  them  firmly 
together,  and  effectually  prevent  any  upward  or  downward 
movement,  especially  the  latter,  which  might  take  place  if 
the  stones  are  of  unsuitable  shape  or  improperly  set,  as  shown 
in  Fig.  42. 


Fig.  42. 


If  the  stones  very  generally,  or  a great  portion  of  them, 
are  thin  and  slab-like  in  form,  they  should  be  set  with  their 
two  largest  and  opposite  surfaces  cross-wise  of  the  road 
and  perpendicular  to  the  road-surface,  showing  in  vertical 


Fig.  43. 

longitudinal  section  as  in  Fig.  43.  The  concrete  will  then 


SHELL  AtfD  CHARCOAL  ROADS. 


10? 


hold  them  firmly  in  place,  even  upon  a wet  and  spongy 
road  bed. 

Shell  Roads. 

Upon  the  South  Atlantic  and  the  Gulf  coasts  of  the 
United  States,  stone  suitable  for  road  coverings  does  not 
exist,  and  in  most  localities  good  coarse  gravel  or  pebbles 
cannot  be  procured  except  at  such  an  outlay  for  transporta- 
tion as  to  practically  exclude  their  employment  for  road 
construction.  Oyster  shells,  however,  can  generally  be  had 
at  from  4 to  5 cents  per  bushel,  exclusive  of  land  haulage, 
and  when  applied  directly  upon  sandy  soil,  as  a covering,  8 
to  10  inches  in  thickness,  they  form  an  excellent  road  for 
pleasure  driving  or  light  traffic.  They  wear  much  more  rap- 
idly, of  course,  than  broken  stone  or  gravel  of  good  quality, 
and  require  more  constant  supervision  to  keep  them  in  good 
order.  When  properly  maintained  they  possess  most  of  the 
essential  requisites  of  a good  road. 

Charcoal  Roads. 

The  novel  expedient  of  using  charcoal  for  road  coverings 
is  not  likely  to  be  resorted  to  except  in  newly  settled,  heavily 
wooded  districts,  where  the  standing  timber  has  no  market 
value,  and  must  be  gotten  rid  of  before  the  land  can  be 
devoted  to  agricultural  pursuits.  A case  is  mentioned  in 
Michigan  where  a good  road  was  made  through  a swampy 
forest  in  the  following  manner  : 

“Timber  from  six  to  eighteen  inches  through  is  cut 
twenty-four  feet  long,  and  piled  up  lengthwise  in  the  centre 
of  the  road,  about  five  feet  high,  being  nine  feet  wide  at  the 
bottom  and  two  at  top,  and  then  covered  with  straw  and 
earth  in  the  manner  of  coal  pits.  The  earth  required  to 


108 


ROADS,  STREETS,  AND  PAVEMENTS. 


cover  the  pile,  taken  from  either  side,  leaves  two  good  sized 
ditches,  and  the  timber  though  not  split,  is  easily  charred  ; 
and  when  charred,  the  earth  is  removed  to  the  side  of  the 
ditches,  the  coal  raked  down  to  a width  of  fifteen  feet,  leav- 
ing it  two  feet  thick  at  the  centre  and  one  at  the  sides,  and 
the  road  is  completed.”  The  material  was  found  to  pack 
well,  not  form  into  ruts,  nor  get  soft  and  spongy  in  wet 
weather,  although  the  water  was  not  drained  from  the 
ditches.  Its  cost  was  $660  per  mile,  and  contracts  for  two 
such  roads  were  given  out  in  Wisconsin  at  $499  and  $520 
per  mile,  respectively.  (See  Gillespie  on  Roads  and  Rail- 
roads.) 


CHAPTER  IV. 


MAINTENANCE  AND  REPAIRS  OP  ROADS. 

It  is  not  considered  to  be  fairly  within  the  scope  of  this 
work,  to  enter  upon  a discussion  of  the  methods  by  which 
the  funds  necessary  for  the  proper  maintenance  of  a public 
highway  shall  be  raised  and  applied. 

The  turnpike  system,  however,  under  which  those  who 
make  the  longest  trips  are  required  to  pay  tolls  foi  keeping 
up  the  road,  is  not  believed  to  be  equitable  in  all  respects, 
nor  the  most  advantageous  to  the  community  living  on  or 
adjacent  to  the  line. 

Many  unthinking  persons  would  be  deterred  from  loca- 
ting upon  a turnpike,  on  account  of  the  tolls  to  which  they 
would  be  thereby  subjected,  regardless  or  ignorant  of  the 
fact  that  their  haulage  and  other  road  expenses  are  likely  to 
be  greatly  augmented  by  their  unwise  selection. 

A judicious  policy  of  road  administration  will  attract 
population  to  the  best  roads,  and  therefore  increase  the 
amount  of  traffic  to  be  accommodated,  and  correspondingly 
lessen  the  expense  per  capita  for  road  maintenance.  Any 
system  which  does  not  secure  these  substantial  results,  if 
not  complicated  by  controlling  circumstances  of  an  adverse 
nature,  must  be  either  inherently  bad,  or  inefficiently  ad- 
ministered. 

The  advantage  of  maintaining  a public  highway  in  excel- 
lent condition,  from  motives  of  economy  alone,  is  a question 


110 


ROADS,  STREETS,  AND  t AVEMENTS. 


which  rarely  receives  that  careful  attention  from  those  having 
the  matter  in  charge,  to  which  its  importance  justly  en- 
titles it. 

The  average  endurance  or  life  of  draught  animals  and  of 
vehicles,  are  functions-^-caleulable  within  reasonable  limits — 
which  enter  directly  into  and  should  in  a great  measure  con- 
trol all  considerations  of  policy  on  this  subject,  since  they 
are  not  oply  not  in  conflict,  but  strictly  coincident  with  the 
most  advanced  humanitarian  views  having  a bearing  on  the 
question. 

*The  traffic  upon  any  given  highway  requires  for  its  ser-. 
vice  a certain  number  of  animals  and  vehicles,  their  number 
depending  in  great  measure  on  the  condition  in  which  the 
road  is  maintained ; and  observation  has  shown  that  the 
amount  of,  improvement  in  the  surface  of  a metaled  or  other 
road,  as  ordinarily  maintained  throughout  the  United  States, 
that  would  enable  eight  horses,  for  example,  to  do  the  work 
of  ten  without  extra  fatigue,  is  greatly  below  the  estimate 
usually  placed  upon  it  by  non-professional  persons. 

If,  for  instance,  we  take  the  case  of  a well-made  broken 
stone  road,  clean  and  dry,  and  compare  it  with  the  same  well- 
made  road  in  a wet  and  muddy  condition,  we  find  that  by 
Macneill’s  formula,  page  29,  a stage  wagon  weighing  1500 
pounds,  in  order  to  carry  a load  of  1500  pounds  at  the  rate  of 
5 feet  per  second  (about  3^  miles  per  hour),  will  require  the 
constant  exertion  of  a force  of  only  94f  pounds  upon  the  dry 
and  clean  road,  while  a force  of  119J  pounds  will  be  required 
to  move  it  at  the  same  rate  over  the  same  road  in  a wet  and 
muddy  state.  This  increase  of  nearly  28  per  cent  in  the  force 
expended  is  due  entirely  to  the  fact  that  the  road  surface  was 
not  kept  clean  by  sweeping  off  and  removing  the  dust. 


COST  OF  NEGLECT. 


Ill 


Hence  if  the  amount  of  traffic  on  a given  length  of 
the  clean  and  dry  road  required  the  daily  service  of  54 
draught  animals,  their  number  would  have  to  be  increased 
to  69,  to  perforin  the  same  amount  of  service  on  the  wet  and 
muddy  road.  If  the  animals  are  driven  singly  there  would 
be  an  addition  of  15  drivers,  and  if  in  pairs  one  half  that 
number.  It  would  perhaps  be  fair  to  assume  5 pairs  and  5 
single  horses,  thus  requiring  10  additional  drivers  on  the 
inferior  road.  A yearly  allowance  of  $225  for  the  purchase, 
feeding  and  care  of  each  animal,  and  the  purchase  and  keep- 
ing up  of  harness  and  vehicle,  would  probably  be  below  the 
actual  cost  in  those  portions  of  the  country  provided,  or  which 
should  be  provided  with  metaled  roads,  amounting  to  $3,375 
per  year  for  the  15  extra  horses  and  the  equipments. 

The  hire  and  support  of  each  driver  may  be  set  down  at 
not  less  than  $35  per  month,  or  $4,200  per  year  for  10 
drivers. 

The  aggregate  amounts  to  the  sum  of  $7,575  per  year  for 
extra  cost  of  service  upon  a wet  and  muddy  road,  for  the 
traffic  of  which  54  horses  would  suffice  if  the  road  were  kept 
clean  of  dust,  and  consequently  clear  of  mud. 

During  those  seasons  of  the  year  when  the  inferior  road 
is  covered  with  dust  only,  but  not  with  mud,  MacneilFs 
formula  shows  a difference  of  not  quite  16  per  cent  in  the 
force  required  to  conduct  the  service,  against  the  dusty  as 
compared  with  the  clean  and  dry  road,  equivalent,  on  the 
same  basis  of  calculation  used  above,  to  an  extra  cost  of 
about  $4,300  per  year  for  the  service  of  animals,  vehicles 
and  men. 

A draught  animal,  properly  taxed,  can  accomplish  upon  a 
fair  road  20  miles  per  day.  from  day  to  day,  without  unusual 


112 


ROADS,  STREETS,  AND  PAVEMENTS. 


or  excessive  fatigue.  If  the  road  under  discussion  connects 
two  towns  10  miles  apart,  one  trip  and  return,  carrying  a 
load  both  ways,  would  be  a day’s  task,  the  total  amount  of 
freight  conveyed  daily  being  the  same  whether  the  road  be 
in  good  condition  or  otherwise. 

It  would  be  carried  by  54  round  trips  daily  on  the  dry  and 
clean  road,  less  than  63  round  trips  on  the  dusty  road,  and  69 
trips  during  the  seasons  when  the  dust  is  converted  into  mud. 

A fair  average  during  the  year,  of  the  extra  cost  of  service 
on  the  inferior  road  (amounting  to  the  rate  of  $4,300  per  year 
while  the  road  is  dusty,  and  to  $7,575  per  year  when  it  is  wet 
and  muddy)  will,  of  course,  vary  within  certain  limits,  with 
the  varying  character  of  the  seasons — with  the  wind,  rain, 
sun,  and  temperature  — but  may,  it  is  believed,  be  mod- 
erately set  down  at  $5,000.  The  traction  upon  a well-con- 
structed and  well-kept  metaled  road,  does  not  vary  materi- 
ally with  varying  moisture  upon  its  surface. 

We  may  therefore  state  the  result  of  the  foregoing  dis- 
cussion as  follows : If  the  traffic  between  two  towns 
connected  by  a well-maintained  metaled  road  10  miles  long 
requires  the  constant  service  of  54  draught  animals,  the  extra 
cost  of  conducting  the  same  traffic  will  amount  to  at  least 
$5,000  per  year  if  the  road  be  allowed  to  become  covered  and 
to  remain  covered  with  dust.  This  greatly  understates  the 
inevitable  results  of  neglect,  inasmuch  as  it  assumes  that  the 
inferior  road  differs  from  the  other  only  in  the  accumula- 
tion of  dust  upon  its  surface,  while  in  point  of  fact  it  will 
soon  wear  into  ruts  and  gutters  which  will  convey  the  sur- 
face water  into  the  road  material,  hastening  the  wear  upon 
the  surface,  and  greatly  increasing  the  expense  of  haulage 
and  the  destruction  of  animals  and  vehicles. 


GOOD  AND  BAD  MAINTENANCE. 


113 


The  foregoing  comparison  has  not  been  made  between 
one  road  in  a superior  condition,  having  a hard  and  smooth 
surface,  and  another  in  a state  so  bad  that  it  might  be  char- 
acterized as  heavy,  soft  and  rough  ; but  the  same  well-con- 
ditioned road-covering  has  been  under  consideration  ; in  one 
case  kept  clean,  and  in  the  other  covered  with  dust  or  mud. 
A road  of  which  the  metal  is  in  good  condition  generally, 
although  covered  with  dust,  is  quite  different  from  a rough, 
soft  and  heavy  road,  terms  which  imply  that  ruts,  gullies, 
and  inequalities  of  various  kinds,  all  of  which  greatly  in- 
crease the  traction  and  the  wear  and  tear  upon  animals  and 
vehicles,  have  been  allowed  to  form,  and  the  dust  and  mud 
to  accumulate  upon  the  surface,  a condition  into  which  any 
good  Macadamized  road  will  degenerate  in  a very  few 
years  if  neglected.  If  a road  in  this  state  be  compared  with 
one  having  a dry,  hard  and  smooth  surface,  such  as  a well- 
maintained  metaled  road  should  possess,  it  will  be  found, 
whether  the  calculations  are  based  upon  the  investigations 
of  Sir  John  Macneill,  or  upon  those  of  M.  Morin,  that  an 
animal  can  draw  about  four  times  as  much  weight,  vehicle 
included,  over  the  good  road,  as  he  can  over  the  bad  one. 

If,  therefore,  a suitable  load  for  2 horses  over  the  good 
road  be  4,000  pounds  carried  on  a vehicle  weighing  2,000 
pounds, — total  6,000  pounds — only  1,500  pounds  could  be 
drawn  by  2 horses  over  the  bad  road,  rendering  it  necessary 
to  add  a third  horse  to  draw  the  vehicle  alone.  These 
results  are  obtained  in  about  the  same  ratio  at  all  rates  of 
speed  not  faster  than  an  ordinary  trot,  and  with  all  kinds  of 
vehicles — carts,  trucks,  stage-coaches,  and  carriages  for  light 
driving. 

If  the  traffic  upon  10  miles  of  good  road  requires  the 


114 


HOADS,  STKEEtS,  AND  LAVEMENTS. 


constant  employment  of  50  horses  and  25  drivers,  at  an 
aggregate  annual  cost  of  $21,750,  (putting  the  cost  and 
support  of  men  and  animals  the  same  as  before,)  it  would 
cost  $87,000  per  annum,  to  conduct  the  same  amount  of 
traffic  upon  the  same  length  of  road  covered  with  deep  ruts 
and  thick  mud,  and  it  would,  beyond  question,  be  a wise 
policy  to  expend  the  whole  excess  of  $55,250,  chargeable  to 
the  bad  road,  in  improving  and  maintaining  this  road  in  a 
superior  condition  of  smoothness  and  hardness,  were  such 
a large  expenditure  necessary  to  secure  that  result  ; for  there 
would  be  saved  thereby,  not  only  this  large  amount,  charge- 
able directly  to  extra  men,  animals,  vehicles,  etc.,  but  money 
expenditures  on  other  accounts  not  easy  to  estimate,  to- 
gether with  the  sacrifice  or  injury  of  local  interests  upon 
which  it  is  difficult  to  put  a money  value  ; such  as  economy 
of  time  due  to  greater  speed  , a longer  endurance  for  ani- 
mals and  vehicles;  the  advantage  of  lighter  and  cheaper 
vehicles  ; freedom  from  excessive  dust  and  mud  ; and  the 
increase  of  population,  and  therefore  of  traffic,  attracted  by 
better  facilities  for  business  intercourse. 

Relation  of  Animal  Force  to  Traffic  on 
Different  Roads. 

The  cost  of  maintaining  a road  in  good  condition,  under 
a given  traffic,  falls  greatly  below  the  extra  cost  of  conduct- 
ing the  same  traffic  upon  a bad  road ; the  ratio  between  the 
two  depending  on  local  prices  of  labor  and  material,  the 
quality  of  the  road  materials  at  command,  and  other  circum- 
stances not  easily  covered  by  a general  rule. 

If  we  assume  that  the  amount  of  traffic  between  the  two 
towns  already  referred  to,  requires  the  constant  service  of  50 


RELATION  OF  ANIMAL  FORCE  TO  TRAFFIC. 


lie 


horses  with  trucks  weighing  2^  tons  inclusive  of  load,  upon 
a very  dry  and  smooth  broken  stone  road,  then  the  additional 
horses  required  upon  other  kinds  and  conditions  of  roads, 
will  be  as  shown  in  the  following  table,  calculated  from  the 
results  of  M.  Morin’s  experiments.  The  influence  upon 
the  force  of  draught  exercised  by  the  character  of  the  vehicle, 
is  omitted,  as,  unnecessary  in  this  discussion. 


Kind  and  Condition  of  Road. 

Relative  num- 
ber of  horses 
required  to 
conduct  a 
given  traffic. 

Broken  stone  road,  very  dry  and  smooth 

50  horses. 

Oaken  platform,  dr  plank  road  in  good  condition.  . 

59  “ 

Broken  stone  road,  moist  and  dusty 

71  “ 

Causeway  of  earth,  or  dirt  road  in  good  condition. . 

93  “ 

Broken  stone  road,  with  ruts  and  mud 

112  “ 

Broken  stone  road,  with  deep  ruts  and  thick  mud. 

192  ' “ 

Solid  causeway  of  earth,  covered  with  gravel  1J4 

inches  thick 

245 

It  may  therefore  be  adopted  as  a well  established  principle, 
that  in  all  communities  where  the  amount  of  traffic  is  sufficien  t 
to  justify  the  construction  of  a good  road  of  any  description,  or 
any  road  that  is  good  of  its  kind,  it  should  be  maintained  in 
a high  degree  of  excellence,  as  a simple  measure  of  economy. 

Macadam  Roads  seldom  well  kept  up. 

It  is  rare:  indeed,  that-  a Macadamized  or  a gravel  road  is 
kept  up  in  the  thorough  manner  above  indicated.  In  the 


116 


110ADS,  STREETS,  AND  PAVEMENTS. 


great  majority  of  cases  the  mud  and  dust  are  allowed  to 
remain  upon  the  road  for  long  periods,  and  are  seldom 
entirely  removed  ; wheel  ruts  are  allowed  to  form  and 
enlarge,  by  reason  of  which  not  only  is  the  resistance  to 
draught,  and  the  wear  and  tear  of  vehicles,  greatly  increased, 
but  the  surface  drainage  is  destroyed  to  such  extent  that  a 
large  portion  of  the  rain-fall  collects  in  the  depressions  and 
finally  percolates  into  the  road  covering  ; the  side  ditches 
become  so  obstructed  that,  in  wet  weather,  water  stands  in 
them  in  places  to  ttie  depth  of  a foot  or  afoot  and  a half,  and 
upwards.  The  result  is  that  during  the  wet  season  the 
road  covering  being  at  its  foundation  only  a few  inches,  if  at 
all,  above  the  level  of  the  water  in  the  side  ditches,  and  re- 
ceiving by  percolation  from  above  a larger  portion  of  the  rain- 
fall, remains  thoroughly  soaked  with  water,  which  causes  it 
to  be  soft  and  heavy.  In  this  condition  it  yields  readily  to 
the  wearing  effects  of  traffic,  loses  its  form  on  the  surface, 
and  soon  becomes  badly  cut  up  with  deep  ruts  and  gullies. 

The  work  ef  repairing  a road  in  the  condition  above 
described,  will  be  substantially  the  same,  whether  due  to 
defective  construction,  subsequent  neglect,  or  to  both  these 
causes  combined  ; except  where  there  was  a failure  to  estab- 
lish the  necessary  sub-drainage  at  the  outset,  in  localities 
requiring  it,  in  which  case  the  repairs  may  practically  amount 
to  a re-construction  of  the  road,  or  nearly  so. 

Assuming,  therefore,  that  the  road  bed  does  not  require 
to  be  disturbed,  or,  in  other  words,  that  it  was  suitably  pro- 
vided with  cross-drains  when  constructed,  or  else  from  the 
character  of  the  soil  did  not  require  them,  the  repairs  should 
be  conducted  in  the  manner  described  in  the  pages  which 
follow. 


TWO  METHODS  OF  ROAD  MAINTENANCES 


11? 


The  Maintenance  of  Broken  Stone  (Macadam) 
Roads. 

The  proper  maintenance  of  a broken  stone  road  consists 
in  preserving  the  smoothness,  hardness,  and  form  of  its  sur- 
face, and  thickness  of  covering,  by  a systematic  restoration 
of  the  materials  that  are  worn  away  by  the  traffic,  and 
removed  in  the  form  of  dust  or  mud. 

The  wear  of  materials  is  not  in  direct  proportion  to  the  aver- 
age daily  tonnage  conveyed  over  the  road,  but  increases  much 
more  rapidly  than  the  tonnage,  other  conditions  being  the  same. 

Two  Methods  of  Maintenance. 

Upon  the  roads  in  France,  which  have  been  the  subject 
of  prolonged  and  careful  observation  by  the  officers  of  the 
Corps  des  Ponts  et  Chaussees,  two  methods  of  maintenance 
are  practiced,  viz  : 

First . The  method  of  minute  daily  repairs  by  which  the 
road  covering  is  preserved  at  a constant  thickness  ; applicable 
to  roads  of  moderate  traffic  upon  which  the  average  daily 
tonnage  does  not  exceed  about  600  tons,  upon  a road  cover- 
ing 18  to  20  feet  wide. 

Second . The  method  of  partial  repairs,  accompanied  by 
periodical  additions  of  material,  by  which  the  diminished 
thickness  of  road  covering  is  restored  at  stated  periods  ; 
adapted  to  roads  of  great  traffic  upon  which  the  daily  tonnage 
exceeds  600  tons  upon  a road  of  the  same  width. 

These  two  systems  will  be  described  separately. 

Maintenance  of  Broken  Stone  Roads  of 
Moderate  Traffic. 

The  thorough  maintenance  of  a stone  road  of  this  class, 


118 


HOADS,  STREETS,  AND  PAVEMEKTS. 


to  such  degree  that  extensive  periodical  repairs  will  not 
become  necessary  requires : 

1.  That  it  should  be  kept  clear  of  dust  and  therefore  cleai 
of  mud. 

2.  That  thorough  drainage  should  be  maintained. 

3.  That  minute  repairs  to  the  surface  should  be  made 
systematically  in  small  patches,  as  often  as,  and  as  soon  as 
ruts  or  depressions  begin  to  show  themselves. 

Under  this  method,  properly  followed,  the  thickness  of 
the  road  covering  will  be  maintained  without  diminution 
for  an  indefinite  time. 

The  mud  and  dust,  or  dirt,  should  be  cleaned  from  the 
surface  and  deposited  beyond  the  side  ditches,  so  as  to  expose 
the  road  metal  slightly  to  view,  without  laying  it  bare,  or 
removing  the  binding  material  from  around  the  stones  at  the 
surface.  This  may  be  done  by  men  suitably  provided  with 
hoes,  stiff  brooms  set  at  right  angles  to  the  handles,  shovels 
and  wheelbarrows. 

The  hoes  should  have  blades  of  hard  wood,  as  those  of 
iron  or  steel,  unless  used  with  the  greatest  care,  might 
loosen  up  some  portions  of  the  stone,  and  needlessly  and 
injuriously  roughen  up  the  surface.  The  brooms  may  be  of 
birch,  willow  or  other  suitable  wood. 

The  sweeping  should  not  be  so  thorough  as  to  remove  the 
detritus,  or  binding  material  from  around  the  stone  slightly 
projecting  above  the  general  surface,  so  as  to  loosen  them  in 
their  position,  and  endanger  their  being  crushed  separately 
piece  by  piece. 

Draught  animals  instinctively  follow  in  the  track  of  pre- 
ceding vehicles,  the  result  being  relatively  excessive  wear,  and 
a tendency  to  form  ruts  along  that  track.  Upon  a road  kept 


MACHINE  SWEEPERS. 


119 


under  watchful  care  this  may  easily  be  prevented  in  sweep- 
ing, by  constantly  effacing  the  wheel  marks. 

Machine-scrapers  and  brooms  of  various  kinds,  drawn  by 
horses,  have  been  used  for  cleaning  the  road  surface,  with 
considerable  saving  in  both  time  and  expense.  It  is  neces- 
sary to  use  them  with  great  care,  in  order  to  avoid  loosening 
the  stones  at  the  surface. 

Mr.  Whitworth,  of  Manchester,  invented  a machine  broom 
for  sweeping  up  the  mud  and  conveying  it  away.  “ It  con- 
sists of  a species  of  endless  broom,  passing  around  rollers 
attached  to  a mud  cart,  and  so  connected  by  cog  wheels  with 
the  wheels  of  the  cart  that,  when  the  latter  is  drawn  for- 
ward, the  broom  is  caused  to  revolve,  and  sweeps  the  mud 
from  the  surface  of  the  road  up  an  inclined  plane  into  the 
cart.”  It  is  drawn  by  one  horse  and  is  said  to  clean  the  sur- 
face better,  cheaper  and  more  quickly,  and  with  less  injury 
to  the  road  and  less  annoyance  to  passengers,  than  it  can  be 
done  by  machine-scrapers,  or  by  hand  labor. 

In  the  city  of  New  York,  and  other  eastern  cities,  street 
sweepers  of  various  devices  have  been  employed,  with  greater 
or  less  saving  of  manual  labor  and  expense.  The  one  that 
has  given  the  best  satisfaction  consists  of  a cylindrical  brush 
or  broom  about  16  inches  in  diameter  and  7 feet  long,  at- 
tached beneath  the  axle  and  connected  by  suitable  gearing 
with  the  wheels  of  a two-wheeled  vehicle  drawn  by  one  horse. 
The  axis  of  the  broom  is  set  horizontally  at  an  angle  of  about 
40  degrees  with  the  axle  of  the  vehicle.  The  rear  end  of  the 
broom  is  therefore  about  44  feet  further  from  the  horse  than 
the  front  end.  When  working,  the  broom  rests  firmly  on 
the  surface  of  the  pavement  or  road-covering  and  revolves  in 
a direction  opposite  to  that  of  the  wheels,  sweeping  the  dust 


120 


ROADS,  STREETS,  AN1)  PAVEMENTS. 


and  mud  sidewise  and  leaving  it  in  a ridge  behind  the  real 
end  of  the  broom,  thus  sweeping  a strip  about  5|-  feet  wide. 
A second  sweeper,  or  a second  trip  of  the  same  sweeper  if 
only  one  is  used,  moves  the  ridge  of  dirt  5|-  feet  further 
toward  the  side  of  the  street  and  widens  the  part  swept 
to  about  11  feet.  In  this  manner  the  dirt  is  finally  delivered 
in  the  side  gutters,  where  it  is  heaped  up  by  hand  with  hoes, 


shoveled  into  carts  and  carried  away.  When  at  work  the 
wheels  and  axle  are  rigidly  connected,  and  revolve  together. 
When  not  sweeping  the  broom  is  raised  up  a few  inches  from 
the  ground  and  the  axle  is  disengaged  from  the  wheels,  when 
both  broom  and  axle  cease  to  revolve. 

This  machine  with  1 horse,  1 driver,  and  10  men  with 


APPLYING  THE  MATERIALS. 


121 


hoes,  will  do  the  work  of  30  men  with  brooms  and  hoes,  the 
shoveling  into  carts  and  carting  away  being  of  course  the 
same  in  both  cases.  These  data  were  obtained  from  an 
inspector  of  police  engaged  in  the  street-cleaning  department 
in  the  city  of  New  York,  and  are  the  results  of  prolonged 
and  careful  observation.  A drawing  of  this  sweeper  is  shown. 
Fig.  44. 

In  using  this  machine  upon  a road,  the  precaution  should 
be  taken  to  see  that  the  brush  is  not  too  stiff.  What  would 
be  entirely  suitable,  and  in  all  respects  well  adapted  for 
sweeping  street  pavements  of  stone  blocks,  wood,  or  asphalt, 
might  injure  the  surface  of  an  ordinary  broken  stone  or  gravel 
road,  by  penetrating  too  deeply,  thereby  loosening  the  stones 
at  the  surface  and  destroying  the  bond.  It  is  important 
that  the  unity  of  surface  should  not  be  disturbed. 

Applying  the  New  Materials. 

The  application  of  new  materials  to  the  road  must  be 
made  not  only  with  system  and  regularity,  but  under  suita- 
ble precautions  and  restrictions,  in  order  to  combine  effi- 
ciency and  economy.  Indeed  the  road  should  be  always 
undergoing  repair,  in  order  that  no  necessity  for  making 
extensive  repairs  can  occur. 

“ Every  road  should  be  divided  into  lengths,  on  each  of 
which  an  intelligent  laborer,  who  thoroughly  understands 
his  business,  should  be  placed,  to  attend  constantly  and  at 
all  times  to  the  proper  state  of  the  road,  and  for  which  lie 
should  be  responsible.  His  office  would  consist  in  keeping 
the  road  always  scraped  clean  and  free  from  mud,  in  filling 
in  any  ruts  or  hollows  the  moment  they  appeared,  with 
broken  stone,  which  should  be  kept  in  depots  or  recesses 
6 


122  ROADS,  STREETS,  AND  PAVEMENTS. 

formed  on  the  sides  of  the  road,  and  one  of  which  should  be 
provided  in  each  quarter  of  a mile.  Those  depots  should  be 
capable  of  containing  about  30  cubic  yards  of  materials,  and 
are  best  when  the  sides  are  formed  with  walls,  so  that  the 
quantity  of  materials  in  them  can  be  easily  ascertained” 
(H.  Law,  C.  E.). 

Each  of  these  men  should  be  provided  with  a wheel-bar- 
row, a shovel,  a pickaxe,  a scraper,  a stiff  broom  and  a 
rammer. 

Upon  roads  that  have  lost  their  proper  transverse  form, 
a level  of  a length  adapted  to  the  width  of  the  roadway, 
should  also  be  provided. 

During  the  autumn  and  spring,  when  the  surface  is 
soft  and  more  work  is  necessary,  additional  men  should  be 
placed  under  the  orders  of  the  permanent  laborers,  but  not 
in  such  manner  as  to  divide  the  responsibility  of  the  latter 
for  the  good  condition  of  the  road  at  all  times. 

The  length  of  road  to  be  given  in  charge  of  one  man 
depends  on  circumstances  varying  greatly  with  the  width  of 
roadway,  the  character  of  the  soil,  quality  of  material  used 
in  repairs,  etc.  Three  miles  a man  would  not  be  too  great 
a length  upon  some  narrow  country  roads,  one  mile  would 
be  a full  allowance  upon  others,  while  upon  the  great 
thoroughfares  near  large  towns,  a small  fraction  of  a mile 
would  be  ample. 

In  France  it  has  been  found  that  one  man  can  sweep  in 
dry  weather  from  260  to  270  lineal  yards  of  road,  5 to  6 yards 
wide,  daily,  if  in  a middling  state,  and  twice  that  area  if  in 
an  excellent  state.  If  he  had  one  and  a half  miles  of  road  in 
charge,  it  could  be  swept  from  one  to  two  times  per  month, 
according  to  its  condition,  which  would  be  quite  sufficient  in 


APPLYING  THE  MATERIAL. 


123 


most  cases,  thus  leaving  from  20  to  25  days  in  each  month 
for  other  work,  such  as  collecting  and  breaking  stone,  con- 
veying it  in  wheel-barrows,  to  the  road,  spreading  and  com- 
pacting it,  and  keeping  the  gutters  and  side  ditches  free. 

A machine-sweeper,  if  employed,  could  be  used  in  com- 
mon upon  several  of  the  sub-divisions  of  the  road.  As  it 
would  not  thoroughly  clean  out  the  ruts  and  depressions, 
especially  if-  these  be  of  considerable  depth,  its  work  would, 
to  some  extent,  have  to  be  supplemented  by  hand  sweeping. 

The  wear  upon  the  surface  of  a well  built  road  is  slow, 
and  so  long  as  the  vehicles  can  be  prevented  from  fol- 
lowing in  each  other’s  tracks,  very  even,  a condition  of 
things  which  can  only  be  maintained  by  careful  watching. 
A slight  and  apparently  unimportant  depression,  if  neglected, 
soon  becomes  a rut,  in  which  the  wear  goes  on  with  an  in- 
creasing rapidity  due  to  the  increasing  force  of  the  blows 
imparted  to  it  as  it  becomes  deeper  and  deeper. 

The  new  material  should  be  added  little  by  little,  from 
lime  to  time  in  the  depressions  and  deficient  places,  and  it 
should  be  broken  fine,  in  comparison  with  that  used  in  the 
original  construction,  containing  all  sizes  and  shapes  upon  to 
the  largest,  which  ought  not  to  exceed  one  inch  and  a half 
in  longest  diameter. 

This  method  is  strictly  one  of  patching,  and  it  should  be 
done  so  constantly,  that  the  small  patches  of  broken  stone 
will  never  exceed  one  to  two  inches  in  thickness,  preferably 
not  more  than  the  thickness  of  one  stone.  If  done  when  the 
i oad  is  firm  and  dry,  the  surface  of  the  depressions  to  be 
filled  should  be  loosened  slightly  with  a light  pick,  to  the 
depth  of  half  an  inch,  so  that  the  layer  of  new  material  may 
promptly  become  united  with  the  old  road,  and  some  of  the 


124 


ROADS,  STREETS,  AND  PAVEMENTS. 


fine  loose  material  can,  with  advantage,  be  taken  out  and 
spread  over  the  broken  stone  as  a binding.  The  loosening 
may  be  dispensed  with  in  most  cases,  when  the  mending 
takes  place  soon  after  a rain,  or  after  sprinkling,  or  when 
the  road  is  in  a soft  condition. 

Frequently  the  tendency  to  form  a rut  may  be  effectually 
arrested  by  sweeping  into  it  the  loose  detritus  from  the  adja- 
cent parts  of  the  road,  and  the  free  and  expert  use  of  the 
rake  and  broom  will  be  found  of  great  advantage  at  all  stages 
of  the  work. 

Penfold  says  that  the  ruts  formed  by  wheels  ought  not  to 
be  filled  up  with  loose  broken  stone,  thus  forming  a ridge  of 
materials  possessing  greater  hardness  than  the  parts  imme- 
diately adjacent  thereto,  but  that  the  rake  should  be  worked 
back  and  forth  across  the  rut  and  on  either  side  of  it,  the 
object  being  to  unite  the  old  loose  material  with  the  new,  in 
some  degree  at  least,  so  that  the  patch  will  be  as  little  unlike 
the  unrepaired  portions  as  possible.  By  this  method  of 
mending,  a cubic  yard  of  stone  will  usually  suffice  for  a 
superficial  rod  of  depressions  and  incipient  ruts.  The  cov- 
ering of  large  areas,  exceeding  eight  to  ten  square  yards, 
should  not  be  undertaken  at  one  time,  and  where  there  are 
several  depressions  inclose  proximity  to  each  other,  the  worst 
should  be  patched  first,  and  allowed  to  get  even  and  solid, 
before  the  others  are  taken  in  hand. 

“ It  is  one  of  the  greatest  mistakes  in  road  making  that  can 
be  committed,  to  lay  on  thick  coats  of  materials,  and  when 
understood,  will  no  longer  be  resorted  to.  If  there  be  sub- 
stance enough  already  in  the  road,  and  which  indeed  should 
always  be  carefully  kept  up,  it  will  never  be  right  to  put  on 
more  than  a stone’s  thickness  at  a time.  A cubic  yard, 


APPLYING  THE  MATERIAL.  125 

nicely  prepared  and  broken,  as  before  described,  to  a rod 
superficial,  will  be  quite  enough  for  a coat,  and,  if  accu- 
rately noticed,  will  be  found  to  last  as  long  as  double  the 
quantity  put  on  unprepared  and  in  thick  layers.  There  is 
no  grinding  to  pieces  when  so  applied  ; the  angles  are  pre- 
served, and  the  material  is  out  of  sight  and  incorporated  in 
a very  little  time.  Each  stone  becomes  fixed  directly,  and 
keeps  its  place  ; thereby  escaping  the  wear  and  fretting 
which  occur  in  the  other  case.”  (Penfold.) 

Even  in  this  patching  process,  rollers  are  sometimes  em- 
ployed for  consolidating  the  stone,  but  by  the  judicious  use 
of  rammers  weighing  from  12  to  20  pounds,  in  conjunction 
with  rakes  and  brooms,  with  which  the  wheel  tracks  are 
promptly  effaced,  and  filled  in,  and  the  new  stone  slightly 
covered  with  detritus  to  bind  it  together,  rollers  may  be  dis- 
pensed with. 

The  deeper  the  depressions  and  ruts  to  be  filled,  the 
larger  the  fragments  of  stone  used  for  repairs  may  be,  up  to 
the  standard  adopted  for  new  roads.  In  a long  continued 
season  of  drought,  the  road  becomes  baked  and  the  metal 
begins  to  loosen  after  a while  and  consequently  wears  away 
with  increased  rapidity.  In  such  cases  great  injury  would 
ensue  unless  precautions  are  taken  to  fix  the  loose  stone  and 
restore  firmness  and  stability  to  the  surface  layer.  This  can 
be  done  effectually  by  moderate  sprinkling  and  light  ram- 
ming or  rolling,  care  being  taken  to  so  regulate  the  supply 
of  water  that  it  shall  resemble  a gentle  shower  of  rain  in  its 
effect  upon  the  surface,  but  not  render  the  draught  heavy. 
Too  much  water,  by  softening  the  binding  layer  on  top, 
allows  the  stones  to  work  upon  each  with  increased  grinding 
power. 


126 


ROADS,  STREETS,  AND  PAVEMENTS. 


This  system  of  maintenance  for  roads  of  moderate  traffic 
seems  open  to  the  objection  of  being  unnecessarily  expensive, 
but  observation  and  experience  have  fully  demonstrated  that 
such  is  not  the  case,  and  that  the  “stitch  in  time”  policy 
applies  here  with  peculiar  and  significant  force.  It  is  not 
only  vastly  cheaper  to  maintain  such  a highway  in  good  con- 
dition, for  a given  traffic  adapted  to  it,  than  to  pay  the  extra 
expense  of  conducting  the  same  traffic  on  a bad  road,  but  it 
is  also  vastly  cheaper  to  keep  the  road  in  excellent  order  than 
it  is  to  restore  it  to  that  state  after  a period  of  injurious 
neglect,  during  which  it  has  become  filled  with  deep  ruts,  and 
thickly  covered  with  dust  and  mud. 

A capital  distinction  must  be  made  between  the  method 
here  inculcated,  which  involves  a constant  and  unceasing 
daily  and  hourly  care  of  a road,  in  order  to  arrest  every  in- 
cipient tendency  to  deterioration  upon  its  surface,  and  any 
and  every  other  method  whatever,  whether  by  frequent 
repairs ; or  only  occasional  repairs ; or  by  repairs  at  long 
intervals.  The  first  only  embraces  the  true  principle,  that  of 
prevention.  All  the  others  are  cures. 

The  French  engineers  of  the  Corps  des  Ponts  et  Chaussees 
were  the  first  to  give  anything  approaching  to  an  exhaustive 
practical  study  to  this  question.  It  was  found  that  in  pro- 
portion as  the  intervals  between  the  periods  of  repairs  were 
shortened  upon  roads  of  small  traffic,  two  important  and 
valuable  results  invariably  followed,  viz.,  that  the  annual  ex- 
pense was  lessened  ; and  that  the  roads  were  always  in  better 
condition  ; and  finally  that  the  roads  were  never  so  good,  nor 
the  expense  of  maintenance  so  small,  as  when  the  system 
of.  unremitting  and  minute  attention  was  in  full  opera- 
tion. 


MAINTENANCE  OF  ROADS. 


12? 


Among  the  statistics  bearing  upon  and  elucidating  this 
branch  of  the  subject,  room  is  here  made  for  the  following 
extract  : 

“ The  following  took  place  with  respect  to  the  high  roads 
of  the  Department  de  la  Sarthe,  somewhat  less  than  250 
miles  in  extent. 

In  1793  a demand  was  made  to  put  them  in  com-  p .j 


plete  order  for £15,280,  or  . . .£60 

In  1824  the  demand  was  above 9,000,  or 36 

In  1836  the  demand  was  above 7,760,  or 31 

In  1839  the  demand  was  above 6,640,  or. . . . 26 


And  the  roads  have  become  better  concurrently  with  the 
reduction  in  cost  of  maintenance,  from  being  in  1793  in 
deep  ruts,  to  1839,  when  they  were  in  very  good  order. 

Part  of  the  great  road  between  Lyons  and  Toulouse,  till 
1833,  was  in  a dreadful  state,  and  yet  it  had  cost  habitually 
about  £110  per  annum  per  English  mile  for  maintenance, 
when  Mr.  Berthault  Ducreux  introduced  a system  of  patch- 
ing instead  of  general  repairs,  since  when,  the  road  was 
gradually  improved,  till  it  was  in  a very  good  state,  and  the 
annual  expense  reduced, by  £13  or  £14  per  mile”  (Gen.  Sir 
John  F.  Burgoyne,  Bart.).  During  the  period  from  1833 
to  1845  the  traffic  on  this  road  never  reached  an  average 
daily  tonnage  of  600  tons.  From  1845  to  1852  it  increased 
to  over  900  tons ; in  1856  it  had  reached  2500  tons  with  a 
steady  increase  still  going  on  until  it  touched  2800  tons, 
when,  upon  the  opening  of  a parallel  railroad  from  Saint 
Etienne  to  Firminy,  it  fell  off  to  about  2000  tons,  which  ifc 
maintained  up  to  the  last  published  reports  in  1865.  It  was 
not  therefore  until  1845  and  subsequent  thereto,  that  the 
amount  of  traffic  on  this  road  was  sufficiently  great  to  render 


128 


ROADS,  STREETS,  AND  PAVEMENTS. 


a change  in  the  method  of  maintenance  either  necessary  oi 
expedient.  This  road  will  be  further  discussed  when  treat- 
ing on  the  method  of  maintenance  by  periodical  reconstruc- 
tion with  intermediate  repairs. 

In  another  case,  that  of  the  road  from  Tours  to  Caen  it 
was  reported  in  May  1836  to  be  in  such  bad  condition  as  to 
require  the  expenditure  of  £2,000  on  the  entire  line,  to  pre- 
vent the  danger  of  its  becoming  impassable.  It  had  been 
the  subject  of  occasional  repairs  from  1832  to  1836,  both 
included,  at  an  annual  cost  of  £978  for  material  and  labor. 

In  January,  1837,  M.  L.  Dumas  of  the  Corps  des  Ponts 
et  Chaussees  was  placed  in  charge  of  it,  when  in  its  worst 
condition.  It  was  afterwards  kept  up  by  the  method  of  con- 
stant and  minute  repairs.  In  August,  1838,  it  was  reported, 
upon  inspection,  to  be  in  a very  good  state,  and  it  subse- 
quently became  better  from  year  to  year,  at  an  average 
annual  cost,  from  1837  to  1841,  a period  of  five  years,  of  £820 
for  labor  and  material. 

In  1834  the  mail  coach  required  five  horses  to  draw  it, 
and  the  service  was  so  severe  upon  them  that  eleven  died 
from  over-work  during  that  year.  After  1838  only  two 
horses  were  necessary  to  draw  the  coach,  which  they  did 
without  loss  of  animals  or  over-fatigue.  Omitting  all  con- 
sideration of  the  cruel  destruction  of  animal  life  inflicted  by 
the  bad  road,  there  was  in  this  case  a saving,  under  the  new 
and  proper  system  of  maintenance,  of  about  12  per  cent  per 
annum  in  the  expense  of  labor  and  material  put  upon  the 
road,  and  250  per  cent  per  annum  in  the  amount  of  annual 
power  required,  for  a specified  item  of  traffic. 


MAINTENANCE  OF  ROADS. 


129 


Maintenance  of  Broken  Stone  Roads  of  large 
Traffic. 

Experience  upon  the  French  roads  seems  to  indicate  that 
when  the  amount  of  traffic  exceeds  600  tons  per  day  over  a 
road  of  16  to  18  feet  width  of  metal,  the  method  of  mainte- 
nance above  described,  by  minute  daily  repairs,  is  not  the 
most  economical. 

The  wear  of  material  is  not  in  direct  ratio  to  the  ton- 
nage passing  over  it.  Other  conditions  remaining  the  same, 
it  augments  much  more  rapidly  than  the  tonnage. 

It  is  believed  that  for  roads  of  great  traffic  the  method  of 
maintenance  by  periodical  reconstruction,  accompanied  by 
partial  repairs  or  patching  during  the  intervals,  offers  supe- 
rior advantages  in  respect  to  cost  of  labor  and  interference 
with  traffic,  to  the  method  by  minute  and  constant  re- 
pairs. 

This  method  consists  in  allowing  the  broken  stone  cover- 
ing to  wear  down  gradually  and — so  far  as  its  wear  can  be 
controlled — evenly,  limiting  the  work  upon  it  to  the  preser- 
vation of  its  unity  of  surface,  by  filling  in  holes,  depressions, 
and  incipient  ruts,  with  small  quantities  of  stone,  not  rising 
above  the  general  surface,  and  therefore  not  intended  to 
restore  that  surface  to  its  original  height.  The  surface  of 
the  road  is  therefore  constantly  kept  in  good  condition,  and 
its  resistance  to  draught  at  a minimum. 

When  the  road  covering,  however,  has  been  worn  down 
to  a thickness  of  4 or  5 inches,  a thorough  repair  to  the  ex- 
tent of  a restoration  of  the  original  thickness  is  made. 

Experience  has  shown  that  the  period  of  this  general 
repair  should  not  be  deferred  beyond  a certain  point,  and 
6* 


130  ROADS,  STREETS,  AND  PAVEMENTS. 

that  re-fillings  of  3 to  4 inches  in  thickness  are  preferable 
to  heavier  ones. 

The  new  layer,  after  being  carefully  spread  to  the  required 
thickness,  should  be  compacted  with  heavy  rollers. 

The  season  of  least  traffic  is  selected  for  this  work,  and, 
in  order  to  lessen  the  interference  with  travel,  the  road-way 
may  be  covered  and  rolled  upon  only  one-half  its  width  at  a 
time,  and  the  rolling  may  be  done  at  night. 

This  method  has  the  advantage  of  providing  a road  sur- 
face which  remains  in  a compact  and  regular  shape  for  a 
long  time  after  each  periodical  rolling  is  completed,  during 
which  only  occasional  and  insignificant  repairs  are  needed. 

Some  practical  precautions,  however,  should  be  ob- 
served, viz.  : 

1.  The  re-laying  and  rolling  should,  if  possible,  be  done 
in  wet  weather.  If  dry  weather  cannot  be  avoided,  the 
road  should  be  sprinkled  rather  copiously,  so  that  the  new 
material  will  unite  readily  with  the  old.  A light  picking 
up  of  the  old  crust  will  help  materially  to  effect  this  union. 

2.  The  new  material  after  being  carefully  spread,  should 
be  repeatedly  sprinkled  and  rolled  until  the  stones  are  well 
pressed  together  into  a compact  layer,  with  an  even  and 
smooth  surface.  Then  a layer  of  sand,  or  stone  dust,  or 
detritus,  not  exceeding  half  an  inch  in  thickness,  is  spread 
over  the  top,  lightly  sprinkled  with  water  and  again  rolled, 
in  order  to  force  it  well  into  the  voids  of  the  new  material. 
It  is  important  not  to  put  too  much  sand  on  at  once.  A 
repetition  of  thin  layers  is  better  than  an  excess  in  the  first 
instance. 

3.  The  wear  of  a road  is  represented  by  the  decrease  in 
the  thickness  of  the  stone  crust,  and  the  only  reliable  means 


MAINTENANCE  OF  ROADS. 


131 


of  finding  this  out  correctly  is  to  take  occasional  soundings 
to  ascertain  not  only  the  thickness,  but  the  composition 
of  the  road  covering,  with  respect  to  solid  material  and 
detritus. 

It  has  become  customary  to  express  the  wear  of  a road 
in  functions  of  its  tonnage  rather  than  of  the  number  of  col- 
lars, for  the  evident  reason  that  a collar  may  represent  only 
half  a ton  upon  some  roads  and  more  than  a ton  upon  others. 
But  even  the  tonnage  is  not  entirely  reliable  as  a basis  of 
comparison,  and  much  depends  on  the  kind  of  material  used 
for  the  road  covering. 

The  following  table  gives  some  of  the  results  obtained 
on  the  roads  in  the  Department  of  the  Loire,  Prance,  from 
1857  to  1860,  as  reported  in  1865,  by  M.  Graeff,  engineer- 
in-chief  des  Ponts  et  Chaussees.  The  road  covering  was 
schist,  and  about  21  feet  in  width. 


Length 
of  road. 

Mode  of  Maintenance. 

Daily 

Tonnage. 

Annual 
wear  in 
cubic  yards. 

1 mile. 

Periodical  reconstruction 

1400 

579 

1 “ 

Minute  and  constant  repairs. . . . 

1400 

727 

1 “ 

Periodical  reconstruction 

1800 

1866 

1 “ 

Minute  and  constant  repairs. . . . 

1800 

2104 

1 “ 

Periodical  reconstruction 

2300 

2794 

1 “ 

Minute  and  constant  repairs. . . . 

3200 

4635 

1 “ 

“ “ “ 

5400 

9934 

Some  of  the  roads  in  the  arrondissement  of  St.  Etienne, 
built  with  basalts,  furnished  the  following  data  : 


132 


ROADS,  STREETS,  AND  PAVEMENTS. 


Length 
of  road. 

Mode  of  Maintenance 

Daily- 

Tonnage. 

Annual 
wear  in 
cubic  yards. 

1 mile. 

Periodical  reconstruction 

1200 

175 

1 “ 

(<  <« 

2000 

372 

1 “ 

Minute  and  constant  repairs.  . . . 

2000 

480 

The  foregoing  tables  show  (1)  that  the  destruction  of 
road  material  increases  much  more  rapidly  than  the  tonnage  ; 
(2)  that  the  tough  basalts  are  much  more  valuable  for  road 
coverings  than  soft  schist  ; and  (3.)  that  for  roads  of  large 
traffic  the  system  of  maintenance  by  periodical  reconstruction, 
accompanied  by  such  intermediate  repairs,  more  or  less  con- 
stantly, as  will  secure  hardness  and  smoothness  of  surface, 
and  uniformly  diminishing  thickness,  is  superior  to  the  one 
of  minute  and  constant  repairs  exclusively.  Indeed,  it  is 
now  generally  admitted  in  France,  that  this  last  named  sys- 
tem is  not  advantageously  applicable  to  roads  upon  which 
the  daily  tonnage  exceeds  600  tons. 

Curves  of  Tonnage  and  Wear. 

The  French  engineers  are  very  careful  and  methodical  in 
collecting  data,  and  arranging  them  in  convenient  form  for 
practical  use.  Having  ascertained  by  careful  and  systematic 
observation,  the  average  daily  tonnage,  and  the  annual  wear 
of  materials  upon  different  portions  of  a road  of  given  width, 
or  upon  different  roads,  curves  may  be  constructed  with  the 
average  daily  tonnage  abscisses,  and  the  quantity  of  material 
worn  out  annually  upon  any  unit  of  length — say  1 mile — as 
ordinates.  A separate  curve  for  each  kind  of  road  material 


CURVES  OF  TONNAGE  AND  WEAR, 


133 


employed  should  be  made,  as  shown  in  the  diagram  Fig.  45, 
which  exhibits  the  results  obtained  on  certain  routes  in  the 
Department  of  the  Loire,  France,  already  referred  to.  The 
wear  of  four  different  kinds  of  stone  was  observed,  viz.,  Schist, 
Quartz,  Granite  and  Basalt.  The  width  of  the  road  cover- 
ing was  21  feet.  The  lower  horizontal  line  gives  the  average 
daily  tonnage  for  different  years,  or  upon  different  portions 
of  the  road  for  the  same  year,  all  measured  from  the  zero 
point  on  the  left.  The  left  hand  vertical  line  shows  the 
yearly  wear  of  road  material  in  cubic  yards  per  mile  of  road. 
The  curve  for  schist  was  obtained  by  M.  Graeff,  who  states 
that  the  deviation  of  the  points  D and  E from  the  general 
curve  may  be  ascribed  to  the  mass  of  detritus  brought  upon 
the  road  by  the  exceptional  traffic  caused  by  the  caving  in  of 
a neighboring  tunnel  on  the  St.  Etienne  and  Lyons  railroad. 
If  the  wear  upon  the  road  was  proportional  to  the  amount 
of  traffic,  the  law  would  be  expressed  by  straight  lines 
instead  of  curves.  The  line  for  schist  would  pass  through 
the  points  0 and  A,  intersecting  the  ordinate  corresponding 
to  a daily  tonnage  of  5400  tons,  at  the  point  M,  indicating 
an  annual  wear  of  only  2097  cubic  yards,  whereas  the  actual 
observed  wear  for  that  amount  of  tonnage  was  9934  cubic 
yards.  The  observations  on  the  wear  of  Quartz,  Granite  and 
Basalt  were  made  by  M.  Montgolfier,  and  although  not  so 
numerous  as  might  be  desired,  being  limited  to  a daily  traffic 
of  1800  tons  for  granite  and  quartz  and  2000  tons  for  basalt, 
they  still  give  an  idea  of  the  relative  value  of  these  materials 
for  road  covering.  The  ordinates  of  these  three  curves  cor- 
responding to  the  abscissa  of  5400  tons  daily  traffic,  were 
obtained  by  calculation,  on  the  assumption  that  the  ordinates 
of  the  several  curves  for  any  one  abscissa  bear  the  same  rela- 


li!4 


HOADS,  STREETS,  AND  PAVEMENTS. 


APPORTIONMENT  OF  MATERIALS. 


135 


tion  to  each  other  as  for  any  other  abscissa.  The  following 
proportion  gives  the  point  K on  the  basalt  curve. 

480  : 1986  : : PK  : 9934 
PK=2405  cubic  yards. 

Besides  the  important  deduction  that  no  road  can  be 
maintained  on  the  hypothesis  that  the  wear  is  proportional 
to  the  tonnage  passing  over  it,  the  diagram  also  shows  that 
the  necessity  for  employing  only  the  best  material,  even  when 
quite  expensive,  increases  rapidly  with  the  tonnage. 


Apportionment  of  Materials. 


The  apportionment  of  repairing  materials,  under  the 
method  of  maintenance  by  periodical  reconstruction,  may  be 
expressed  by  the  formula  nxC=A  + nxE,  in  which  n=the 
number  of  years  intervening  between  the  periods  of  recon- 
struction or  rolling. 

C=the  number  of  cubic  yards  of  wear  per  year,  per 
mile. 

E=the  mean  number  of  cubic  yards  per  year,  per  mile, 
for  small  repairs. 

A=  the  mean  number  of  cubic  yards  required  for  rolling. 
C and  A become  known  for  each  road  by  careful  observa- 
lion  for  a sufficient  length  of  time.  E varies  from  year  to 
/ear  during  a period  of  n years,  being  smallest  in  the  year 
mmediately  succeeding  a re-rolling,  and  largest  in  the  year 
preceding  the  next  rolling.  In  practice  E will  never  exceed 
g-  0,  but  will  increase  from  zero  to  ^ C in  n years,  with  a 
mean  average  value  of  \ C,  from  which  there  results  the 


practical  rule  of 


4 A 
3C* 


It  maybe  assumed  that  of  the  whole  quantity  of  materia;] 


136 


ROADS,  STREETS,  AND  PAVEMENTS. 


required  for  one  period,  by  this  system  of  maintenance,  25 
per  cent  will  be  consumed  in  small  repairs,  and  75  per  cent 
in  one  mass  for  re-rolling,  and  that  the  period  lasts  2 years. 

It  is  the  opinion  of  M.  Graeff  that  upon  roads  of  large 
traffic  this  system  of  maintenance,  as  compared  with  the  one 
of  constant  repairs,  effects  a saving  of  material  that  may,  in 
some  cases,  amount  to  40  per  cent ; and  that  during  a period 
of  three  and  a half  years,  upon  certain  observed  roads  in  the 
Department  of  the  Loire,  the  saving  of  labor  was  10  per  cent. 

Maintenance  of  Gravel  Roads. 

The  maintenance  and  repairs  of  road-coverings  composed 
of  gravel,  or  of  a mixture  of  gravel  and  broken  stone,  may 
be  conducted  upon  the  same  principles,  and  by  the  same 
methods  applicable  to  those  of  broken  stone. 


CHAPTER  Y. 


STREETS  AND  STREET  PAVEMENTS. 

A street,  in  a city  or  town  where  the  best  ordered  modern 
devices  for  promoting  the  comfort,  convenience  and  health 
of  the  inhabitants  have  been  introduced,  should  provide, 
upon  and  beneath  its  surface,  (1)  for  the  accommodation  of 
ordinary  travel  and  traffic,  (2)  for  the  drainage  of  the  surface 
and  subsoil,  (3)  for  conveying  away  the  faecal  and  liquid 
refuse  called  sewage,  and  (4)  for  conducting  water  and  gas 
to  the  inhabitants. 

The  subject  of  providing  facilities  for  carrying  on  the 
necessary  travel  and  traffic  of  a street,  by  suitably  draining 
and  paving  its  surface,  is  properly  embraced  in  the  design 
and  scope  of  this  work.  A few  brief  suggestions  with  regard 
to  sewerage  and  sub-drainage  will  not  be  out  of  place,  before 
proceeding  to  a description  of  street  pavements. 

The  importance  of  sewers  in  their  relation  to  the  health 
of  a people  cannot  well  be  overstated.  Those  of  ancient 
times  were  generally  designed  to  receive  and  convey  away 
both- the  faecal  refuse  and  surface  water,  and  those  of  some 
of  the  best  sewered  cities  of  the  present  day  have  been 
planned  and  constructed  with  the  same  objects  in  view. 
The  early  sewers  of  England  carried  off  the  surface  drainage 
only,  the  faecal  matter  being  generally  collected  in  cess-pools 
located  beneath  or  very  near  the  habitations  of  the  people, 
until  the  year  1847,  when  it  was  made  obligatory  to  pass  it 


138 


ROADS,  STREETS,  AND  PAVEMENTS. 


into  the  sewers.  In  districts  where  the  sewage  is  used  foi 
enriching  the  land,  the  question  of  its  separation  from  the 
rain-fall  may  be  an  important  one.  On  the  other  hand  the 
surface  drainage  of  streets  that  are  closely  built  up,  or  where 
the  traffic  is  heavy,  is  quite  as  impure,  in  time  of  moderate, 
or  during  the  first  stages  of  heavy  rain-fall,  as  any  sewage, 
and  it  might  be  unwise  to  allow  all  of  it  to  flow  directly  into 
the  fresh  water  courses  of  the  neighborhood,  in  localities 
where  the  purity  of  those  streams  could  be  preserved  by 
passing  it  into  the  sewers.  In  some  cases  the  sewers  take 
only  the  moderate  rain-falls,  the  rain-fall  pipes  being  so 
arranged  that  when  their  contents  attain  a certain  velocity, 
the  sewer  ceases  to  intercept  it  in  whole  or  in  part.  Cir- 
cumstances of  a local  character,  will  control  the  plan  and 
details  of  a system  of  sewerage,  to  such  degree,  that  no  uni- 
versal rules  for  the  guidance  of  the  engineer  can  be  laid  down, 
although  there  are  some  general  principles  applicable  to 
every  locality.  Even  when  the  question  of  the  manurial 
value  of  the  sewage  is  to  be  considered,  it  will  not  always  be 
judicious  “to  convey  the  rain-fall  to  the  rivers  and  the  sew- 
age to  the  land,”  which  is  advocated  by  some  sanitary  writers 
as  an  unexceptionable  rule. 

Inasmuch  as  sewers  are  or  should  be  water  tight,  as 
otherwise  the  contamination  of  the  surrounding  soil,  and 
consequently  of  the  atmosphere,  by  leakage,  would  be  the 
certain  result,  they  in  no  sense,  when  properly  constructed,  act 
as  drains,  by  lowering  the  subsoil  water-level.  In  well  paved 
streets  very  little  of  the  rain-fall  is  absorbed  into  the  soil, 
but  finds  its  way  into  the  sewer,  or  other  channels  provided 
for  it,  and  were  it  not  for  the  unpaved  areas,  including  back 
yards  and  unimproved  lots,  the  question  of  draining  the  soil, 


DRAINAGE  OF  SUB-SOtL. 


139 


in  built-np  streets  would  not,  perhaps,  possess  great  impor- 
tance, especially  if  the  soil  be  of  a sandy  or  gravelly  character. 

It  has  been  shown  in  Great  Britain,  from  carefully  pre- 
pared statistics,  that  the  death  rate  from  pulmonary  diseases 
was  reduced  50  per  cent  by  sewering  certain  towns  in  such 
manner  as  to  lower  the  subsoil  water  by  drainage,  while 
in  other  towns  sewered  with  impervious  pipes  through- 
out, with  no  provision  for  drainage,  there  was  no  decrease 
in  the  death  rate  from  consumption.  Some  provision  for 
subterranean  drainage  should  therefore  be  made  without 
using  the  sewers  for  that  purpose,  although  the  laying  of 
sewers  alone,  by  cutting  through  the  various  impervious 
strata,  invariably  results  in  the  drainage  of  the  surrounding 
earth  to  a greater  or  less  degree. 

It  is  easy,  when  constructing  the  sewers,  to  arrange  an 
effective  system  of  subsoil  drainage,  generally  at  a moderate 
cost.  There  are  several  ways  of  doing  this,  among  which 
the  following  may  be  mentioned  : 

First . The  method  by  perforated  inverts,  gives  when 
the  invert  blocks  are  laid,  a series  of  continuous  channels  in 
the  lower  portion  of  the  sewer.  The  joints  between  the 
invert  blocks  are  left  open  on  the  sides  and  bottom,  but  are 
closely  filled  and  pointed  with  mortar  between  the  sewer  and 
the  longitudinal  channels,  to  prevent  the  escape  of  sewage 
into  the  latter. 

Second . Make  the  foundation  of  the  sewer  itself  serve 
the  purpose  of  a blind  drain,  by  forming  it  of  well  com- 
pacted broken  stone  of  various  sizes.  Between  the  broken 
stone  and  the  earth  on  either  side,  a vertical  layer  of  straw, 
hay,  or  fine  brush  may  be  placed,  to  prevent  the  choking  of 
the  drain  with  soil. 


140 


ROADS*  STREETS,  AND  PAVEMENTS. 


Third . Make  a blind  drain  on  each  side  of  the  sewer, 
by  filling  in  with  broken  stone  or  a mixture  of  stone  and 
coarse  gravel,  instead  of  ordinary  soil. 

Fourth . An  ordinary  drain  of  brick  like  any  of  those 
shown  on  page  5G,  or  a tile  drain,  on  each  side  of  the 
sewer  foundation  will  answer  as  well  as  any  other,  and  can 
easily  be  laid  at  less  cost  than  a blind  drain  of  stone. 
Whatever  method  be  adopted,  it  should  be  such  as  will  secure 
a thorough  drainage  of  the  soil  to  the  level  of  the  floor  of 
adjoining  cellars.  The  areas  in  rear  of  the  houses  may  be 
drained  by  either  tile,  brick,  or  blind  drains,  connected  by  a 
single  pipe  with  the  house  drain,  and  thence  with  the  sewer. 
As  the  arrangement  of  these  drains,  their  relation  to  the  soil 
pipes,  and  the  location  and  design  of  the  necessary  traps 
and  ventilating  shafts,  to  prevent  the  escape  of  sewage  gases 
into  the  houses,  belong  to  the  province  of  the  sanitary  engi- 
neer, no  further  reference  to  them  need  be  made  here. 
The  treatment  of  the  street  surface  will  next  be  considered. 

Street  Pavements. 

It  is  desirable,  for  several  reasons,  that  the  surfaces  of 
streets  through  large  towns  and  cities  should  be  paved. 

The  essential  requisites  of  a good  street  pavement  are, 
that  it  shall  be  smooth  and  hard  in  order  to  promote  easy 
draft ; that  it  shall  give  a firm  and  secure  foothold  for 
animals,  and  not  become  polished  and  slippery  from  use ; 
that  it  shall  be  as  noiseless  and  as  free  from  mud  and  dust 
as  possible ; and  that  it  shall  be  easily  cleansed,  and  shall 
not  absorb  and  retain  the  surface  liquids,  but  facilitate  their 
prompt  discharge  into  the  side  gutter  catch-basins.  It 
should  also  be  of  such  material  and  construction,  that  it 


ROADS  FOR  PARRS. 


141 


can  be  readily  taken  tip  in  places,  and  quickly  and  firmly 
relaid*  so  as  to  give  easy  access  to  water  and  gas  pipes. 
Facility  of  repairs  at  all  seasons  of  the  year  is  another  impor- 
tant requisite.  Economy  of  maintenance  and  repair  require 
that  the  material  at  the  surface  shall  be  durable. 

All  the  road  coverings  heretofore  described  are  wanting 
in  one  or  more  of  the  most  important  of  these  qualities,  while 
they  possess  beyond  doubt,  some  of  those  that  are  least  essen- 
tial, in  even  a greater  degree  than  the  best  street  cover- 
ings. 

Eoad  surfaces  of  broken  stone  or  gravel,  produce  less 
noise,  and  give  a more  secure  footing  for  horses  than  blocks 
of  stone  or  wood,  or  a continuous  surface  of  asphalt  or  other 
material,  but  they  require  such  constant  supervision  to  arrest 
the  formation  of  ruts,  and  are  so  infested  with  either  dust 
or  mud,  as  to  render  them  greatly  inferior  to  a good  stone  or 
asphalt  pavement  for  streets  subjected  to  heavy  traffic.  An 
exception  may  perhaps  be  made  in  their  favor  upon  sub- 
urban streets  so  extensively  devoted  to  light  travel  or  pleas- 
ure driving,  as  to  justify  the  expense  of  frequent  sprinkling 
by  day  and  sweeping  by  night.  These  kinds  of  road 
coverings  are  also  conceded  to  be  excellent  for  the  drives 
in  public  parks,  and  there  are  cases  where  the  principal 
thoroughfare  leading  thereto  should  be  constructed  after 
the  same  method,  and  maintained  with  the  same  care,  as  the 
park  drives,  especially  if  the  bulk  of  the  travel  and  traffic 
over  it  be  of  a light  character.  They  should  be  swept  every 
night,  and  in  dry  weather  sprinkled  repeatedly  during  the 
day.  Carts  conveying  the  materials  for  repairs,  whether 
gravel  or  broken  stone,  should  be  kept  constantly  upon  the 
street,  especially  during  those  hours  when  it  is  least  fro- 


142  ROADS,  STREETS,  AXD  PAVEMEKTS. 

quented,  so  that  all  ruts  and  depressions  may  be  promptly 
filled  as  soon  as  they  begin  to  appear. 

It  must  be  admitted,  however,  that  there  appears  to  be 
no  trustworthy  record  of  any  urban  street  of  this  kind, 
in  a thickly  settled  district,  which  has  been  maintained  in 
such  manner,  that  the  inconvenience  and  annoyance  inflicted 
by  dust  and  mud  upon  the  residents  or  people  doing  business 
on  either  side,  did  not  in  reality  amount  to  a most  serious 
public  nuisance. 

Pavement  Foundations. 

The  object  of  a pavement  being  to  secure  a hard,  even 
and  durable  surface,  and  not  to  any  considerable  extent,  nor 
necessarily,  to  support  the  weight  of  heavy  loads,  it  is  evident 
that  the  surface  will  soon  subside  unequally,  forming  ruts 
and  depressions,  unless  it  rests  upon  a firm  and  solid  founda- 
tion. A good  foundation  is  as  necessary  for  the  stability  of 
a pavement  as  for  that  of  any  other  construction. 

Bad  foundations  invariably  produce  bad  pavements 
sooner  or  later,  while  with  a good  foundation  the  quality  of 
the  surface  upon  which  the  wear  takes  place,  depends  upon 
the  material  used  for  paving,  and  the  manner  of  laying  it 
down. 

Among  the  suitable  foundations  for  a pavement,  provided 
the  thickness  be  adapted  to  the  character  of  the  subsoil  and 
the  nature  of  the  traffic,  are  the  following:  (1)  Hydraulic 
concrete,  six  to  eight  inches  in  thickness  ; (2)  rubble  stones 
set  on  edge,  but  not  in  contact,  with  the  interstices  filled  in 
with  concrete  ; (3)  rubble  stones  set  in  contact,  on  edge,  like 
the  sub-pavement  of  a Telford  road  ; (4)  cobblu  stones  firmly 
set  in  a form  of  sand  or  gravel ; (5)  small  rubble  stones 


FOUNDATIONS. 


143 


of  random  sizes,  in  a well-compacted  layer ; or  (6)  a layer 
of  broken  stone  laid  in  the  manner  of  a Macadamized 
road. 

Sand  foundations  are  in  most  common  use.  They  are 
described  below.,  in  the  paragraphs  on  cobblestone  pavements. 

Foundation  of  Broken  Stone. 

Broken  stone  foundations  are  prepared  in  all  essential 
respects  like  a Macadamized  road.  They  should  generally 
be  not  less  than  8 to  10  inches  thick,  or  the  usual  thickness 
of  a good  road  covering  of  broken  stone.  If  the  soil  be  of  a 
yielding,  soft  nature  like  most  clays,  there  should  be  a sub- 
foundation of  sand  or  gravel,  suitably  rammed  in  layers,  for 
the  broken  stone  to  rest  upon.  After  the  first  layer  of  stone 
is  spread  upon  the  excavated  road-bed  or  upon  the  sand  form, 
the  street  may  be  opened  to  traffic,  or,  to  hasten  the  opera- 
tion of  consolidation,  rollers  may  be  used  upon  it.  A second 
and  a third  layer  follow.  In  spreading  the  last  layer,  the 
required  form  of  transverse  section  of  the  road  surface  is 
carefully  established.  The  foundation  is  finished  with  a 
layer  two  to  three  inches  thick  of  clean  gravel,  and  the 
pavement  is  laid  thereon,  as  hereinafter  described. 

Foundation  of  Cobble  Stones. 

The  cobble  stone  pavement  set  in  a sand  form,  of  which  a 
description  is  given  below,  although  furnishing  a very  inferior 
street  surface  for  the  reasons  therein  given,  forms  a good  foun- 
dation for  a pavement  of  stone  blocks,  and  has  frequently  been 
utilized  as  such  in  the  reconstruction  of  old  cobble  stone  roads. 

In  setting  the  cobble  stones  less  care  would  be  necessary 
in  their  selection  with  a view  to  placing  those  of  the  same 


144 


ROADS,  STREETS,  AND  PAVEMENTS. 


size  together,  than  if  they  were  themselves  to  form  the  road 
surface  and  sustain  the  traffic. 

The  Cobble  Stone  Pavement. 

The  cobble  stone  pavement  is  the  one  in  most  general 
use  in  the  United  States,  especially  in  new  towns  and  cities, 
though  entirely  wanting  in  most  of  the  essential  requisites 
of  a good  street  surface.  It  is  formed  of  rounded  or  egg- 
shaped  hard  pebbles,  varying  in  length  from  6 to  10  inches, 
and  in  width  from  3 to  6 inches.  They  are  set  side  by  side, 
in  close  contact  with  each  other,  with  their  smallest  ends 
down,  in  a bed  or  form  of  clean  damp  sand  or  small  gravel, 
previously  compacted  in  layers  upon  the  natural  soil. 

This  sand  foundation  should  be  from  8 to  10  inches  in 
depth,  depending  on  the  nature  of  the  sub-soil.  Before 
forming  it,  the  road  bed,  after  it  has  been  excavated  to  the 
proper  depth,  is  thoroughly  consolidated  by  ramming  or  roll- 
ing. The  sand  should  be  compacted  while  in  a moist  state. 

The  cobble  stones,  after  being  set  in  position,  are  firmly 
settled  to  their  beds  by  a heavy  rammer,  so  as  to  bring  their 
tops  to  the  required  roadway  surface.  Several  rammings 
are  sometimes  necessary  to  secure  their  even  adjustment.  It 
is  usual  to  give  the  required  convexity  to  the  surface — about 
1 in  40  to  45  from  the  centre  to  the  side  gutters — by  placing 
the  largest  stones  in  the  middle,  and  suitably  graduating  the 
sizes  toward  the  sides. 

After  the  pavement  is  laid  a layer  of  sand  or  fine  gravel, 
two  or  three  inches  thick,  is  spread  upon  the  surface  and 
allowed  to  work  its  way  in  between  the  stones. 

The  defects  of  this  kind  of  pavement  are  that  its  resist- 
ance to  traction  is  great,  while  it  is  noisy,  rough,  and  diffi- 


COBBLE  STONE  PAVEMENT. 


145 


cult  to  clean.  The  stones  are  liable  to  be  pressed  down 
unequally  into  the  sand  foundation,  resulting  in  ruts  and 
depressions  which  necessitate  frequent  repairs.  It  is  severe 
upon  vehicles  and  animals,  and  very  unpleasant  to  travel 
over. 

In  laying  cobble  stone  pavements  in  the  city  of  New 
York,  the  usual  requirements  are  that  “The  paving  stones 
must  be  heavy  and  hard,  and  not  less  than  six  inches  in 
depth,  nor  more  than  ten  inches  in  any  direction.  Stones 
of  similar  size  are  to  be  placed  together.  They  are  to  be 
bedded  endwise  in  good  clean  gravel,  twelve  inches  in  depth. 
They  shall  all  be  set  perpendicularly,  and  closely  paved  on 
their  ends,  and  not  be  set  on  their  sides  or  edges  in  any 
cases  whatever.5'* 

Sand  is  unsuitable  for  a foundation,  except  when  in  a 
confined  position  where  it  cannot  spread  or  escape  laterally, 
as  is  usually  the  case  when  compacted  in  the  excavated  road 
bed.  It  should  be  clean,  and  if  mixed  with  gravel,  screened 
from  all  grains  exceeding  one-fifth  of  an  inch  in  diameter, 
and  compacted  in  the  foundation  while  moist,  by  ramming 
or  rolling  it  in  layers  not  exceeding  four  inches  in  thickness. 
When  all  these  conditions  are  imposed  it  forms  a cheap  and 
tolerably  good  foundation  for  a pavement. 

Sand  from  the  sea  shore,  or  beach  sand,  from  which  all 
earthy  matter  has  been  washed,  cannot  be  thoroughly  com- 
pacted by  ramming,  on  account  of  the  entire  absence  of  co- 
hesion among  the  grains,  which  causes  it  to  slide  from  under 
and  loosen  up  around  the  rammer  at  each  blow.  Sand  of 
this  quality  should  be  consolidated  by  rolling,  or  if  rollers 
cannot  be  had,  clayey  or  earthy  matter  should  be  mixed  with 
'tin  such  proportions  as  experience  in  each  case  may  suggest. 


140 


ROADS,  STREETS,  AND  PAVEMENTS. 


Old  Roads  as  Foundations. 


An  old  road,  whether  it  be  payed,  Macadamized  or 
graveled,  will  generally  be  found  to  furnish  a good  founda- 
tion for  a new  pavement,  care  being  taken  to  bring  its  sur- 
face to  an  even  state,  and  to  the  required  form,  by  removing 
all  large  elevations  and  depressions.  If  the  old  covering  be 
cobble  stones,  the  interstices  at  the  surface  should  be  cleaned 
out  and  then  filled  with  clean  sand  or  small  gravel,  well 
compacted,  or,  better  still,  with  hydraulic  mortar,  or  »vith 
concrete  of  which  the  ballast  contains  no  fragments  or  gravel 
exceeding  half  an  inch  in  largest  diameter. 

Rubble  Stone  Pavement. 

The  rubble  stone  pavement  (Pig.  46),  resembling  the 
nncoursed  portion  of  some  ancient  opus  incertum,  is  formed 
ivith  fragments  of  stone  of  various  shapes  and  sizes,  laid 


made  more  even.  It  will  therefore  offer  less  resistance  to 
traction,  and  be  less  severe  upon  vehicles  and  animals.  The 
fragments  of  stone  are  such  as  can  usually  be  selected,  or  pro- 
duced with  very  little  labor  from  the  refuse  of  a stone  quarry. 
The  dimensions  may  vary  from  3 to  6 inches  in  breadth  and 
6 to  12  inches  in  length,  while  the  depth,  to  prevent  their 
tilting  up,  should  not  be  less  than  5 or  6 inches.  They 
are  laid  like  cobble  stones,  in  a form  of  sand  or  gravel,  each 
stone  being  carefully  adjusted  to  its  place,  so  that  when  it 


Fig.  46. 


closely  and  compactly  together,  so  as 
to  form  as  even  a surface  as  possi- 
ble, but  not  in  lines  or  courses.  It 
is  superior  to  the  pavement  of  round- 
ed pebbles,  inasmuch  as  it  may  be 


CONCRETE  FOUNDATIONS. 


147 

has  been  properly  rammed  its  top  face  will  coincide  with 
the  required  surface  of  the  pavement.  Continuous  joints  in 
the  direction  of  the  draught  should  be  avoided,  in  order  to 
guard  against  the  tendency  to  wear  into  ruts.  To  this  end 
the  long  stones  should  not  be  set  with  their  largest  dimen- 
sions parallel  to  the  sidewalks. 

A rubble  stone  pavement  laid  in  the  manner  above  indi- 
cated, forms  a good  foundation  for  a pavement  of  stone 
blocks,  and  they  may  be  laid  upon  a layer  of  sand  or  gravel 
about  one  inch  thick,  or  in  a bed  of  cement  mortar,  preferably 
the  latter,  although  attended  with  some  extra  expense. 

Concrete  Foundations. 

Foundations  of  concrete,  for  street  pavements,  may  be  laid 
by  the  same  method,  and  the  concrete  should  be  made  after 
the  same  formula  already  laid  down  for  roads,  except  that 
they  should  generally  be  somewhat  thicker,  to  enable  them  to 
withstand  the  heavy  traffic  which  passes  over  them  in  most 
cities  and  large  towns.  Upon  firm  and  nearly  incompress- 
ible soils,  a thickness  of  6 to  7 inches  properly  rammed  in 
one  or  two  layers,  will  ordinarily  suffice,  but  in  soils  of  a 
spongy,  elastic  nature,  or  largely  composed  of  clay,  a thick- 
ness of  8 to  9,  or  even  10  inches,  will  not  be  excessive. 
Though  the  most  costly,  it  is  the  best  street  foundation,  all 
things  considered,  that  has  yet  been  devised.  In  a few  weeks 
after  laying  it  becomes  a strong,  solid  monolith,  and  even  if 
it  should  crack  in  many  places,  in  consequence  of  the  great 
and  varying  loads  upon  it,  or  from  unequal  powers  of  resist- 
ance, and  therefore  unequal  subsidence  of  the  underlying 
soil,  its  superiority  to  any  other  kind  of  bottoming  can 
scarcely  be  doubted.  Perhaps  not  the  least  of  its  manj 


148 


ROADS,  STREETS,  AND  PAVEMENTS. 


advantages  is  the  protection  it  affords  against  frost  in  high 
latitudes,  subjected  to  long  continued  cold  weather,  such  as 
prevailed  in  the  northern  portions  of  the  United  States, 
and  in  the  Canadas  during  the  winter  of  1874-5.  It  was 
then  observed  that  in  Broadway,  New  York  city,  where  the 
stone-block  pavement  rests  upon  a concrete  foundation,  the 
water  and  gas  pipes  were  almost  entirely  exempt  from  injury 
by  frost,  while  in  the  side  streets,  and  notably  in  Fifth  Avenue, 
which  is  covered  with  the  Belgian  blocks  set  in  a sand  foun- 
dation, the  pavement  had  to  be  taken  up  to  such  an  extent, 
and  in  such  numerous  places,  as  to  cause  serious  annoyance 
to  the  traffic,  to  say  nothing  of  the  expense  incurred  in 
repairs,  and  the  permanent  injury  to  the  street.  It  is  im- 
possible to  take  up  a pavement  in  places,  and  relay  it  in  the 
same  condition  in  which  it  was  found. 

Rubble  Stone  Foundations. 

Bubble  stone  foundations  for  street  pavements  are  con- 
structed in  essentially  the  same  manner  as  for  roads.  Their 
thickness,  however,  should  rarely  be  less  than  8 to  10  inches, 
and  they  should  not  be  resorted  to,  if  the  road  bed  is  com- 
posed of  easily  compressible,  or  spongy  soil,  in  which  the 
stones  comprising  the  lower  layer  would  fail  to  find  a firm 
and  stable  bed. 

After  the  stones  have  been  laid  down  to  the  required 
thickness,  the  surface  should  be  made  as  even  as  possible,  by 
breaking  the  stones  of  the  top  layer  into  small  fragments,  so 
as  to  fill  on  the  surface  interstices.  For  this  work  the  long- 
handled  hammer  described  on  page  73,  will  be  found  to 
answer  very  well.  There  should  then  be  spread  on  the  sur- 
face a layer,  2 or  3 inches  in  thickness,  of  binding  material, 


SIDEWALKS  AND  GUTTERS. 


149 


such  as  the  detritus  of  the  stone  yards,  or  a mixture  of  clay, 
sand  and  gravel,  or  ordinary  hard  pan,  or  unscreened 
gravel. 

The  road  may  then  be  thrown  open  to  traffic,  or  compacted 
by  rollers,  the  ruts  and  depressions  being  constantly  raked 
in.  When  the  surface  has  become  hard,  smooth  and  even, 
a layer  of  about  2 inches  in  thickness  of  clear  gravel  is  evenly 
spread  thereon  to  receive  the  paving  blocks.  The  top  surface 
should  be  adjusted  parallel  to  that  of  the  finished  street. 

This  foundation,  therefore,  is  nothing  more  than  a sub- 
stantial road  covering,  consisting  of  a rather  deep  bottoming 
of  rubble  stone,  surmounted  with  a thin  surface  finish  of 
Macadam  stone  and  binding  material. 

Foundations  of  Rubble  Stone  and  Concrete. 

Pavement  foundations  of  rubble  stone,  filled  in  with 
cement-concrete,  formed  after  the  general  directions  given 
on  page  105,  doubtless  rank  next  to  those  of  cement-concrete 
alone,  in  firmness  and  durability.  Their  thickness  may  vary 
from  6 to  8 inches,  if  the  road  bed  be  mostly  clay  of  a yield- 
ing character,  or  if  it  be  elastic  or  spongy. 

In  order  to  economize  in  the  cost  of  the  concrete  filling, 
care  should  be  taken  when  laying  down  the  rubble  stones,  to 
adjust  their  upper  edges  somewhat  evenly,  so  as  generally  to 
bring  them  into  a surface  parallel  to  that  of  the  finished  street. 

Sidewalks  and  Side  Gutters. 

For  the  convenience  of  foot-passengers,  streets  must  be 
provided  with  sidewalks,  on  either  side.  Their  width, 
which  will  depend  upon  the  space  that  can  be  spared  from 
the  carriage  way,  the  kind  of  traffic  carried  on  in  the  locality, 


150 


ROADS,  STREETS,  AND  PAVEMENTS. 


and  the  number  of  people  requiring  daily  accommodation, 
should  seldom  be  less  than  six  feet,  or  more  than  fifteen. 
They  are  usually  paved  with  flagging  stones,  brick,  asphalt, 
wood,  or  cement-concrete,  or  some  other  variety  of  artificial 
stone,  as  described  in  Chapter  VI.  and  should  slope  toward 
the  street  not  less  than  1 inch  in  nine  or  ten  feet,  in  order 
that  the  surface  water  may  be  conveyed  promptly  into  the 
side  gutters. 

The  carriage  way  is  separated  from  the  sidewalk  by  a 
line  of  flagging-stones,  sunk  into  the  ground  on  their  edges. 
These  are  called  curb-stones,  and  form  the  outer  side  of  the 
sidegutters  and  sustain  the  sidewalk,  with  the  pavement  of 
which  their  upper  edges  are  set  flush,  so  that  the  water  can 
flow  over  them  into  the  gutters.  Their  lower  edge  should 
extend  at  least  6,  and  preferably  8 or  10  inches  below  the 
surface  of  the  street  pavement,  to  which  they  act  as  a kind 
of  abutment. 

It  is  usual  to  pave  with  special  care  for  a width  of  14 
to  16  inches,  the  lowest  portions  of  the  street  on  either 
side,  called  the  side  gutters,  where  the  pavement  meets 
the  curb-stones.  The  slabs  used  for  this  purpose,  called 
gutter-stones,  or  simply  gutters,  are  laid  flatwise,  so  that 
their  upper  faces  form  a part  of  the  street  surface.  In 
the  city  of  New  York  the  curb-stones  for  the  best  paved 
streets  are  required  to  be  not  less  than  3 feet  long,  20  inches 
wide,  and  5 inches  thick;  and  the  gutter-stones  not  less 
than  3 feet  long,  14  inches  wide  and  6 inches  thick.  In 
streets  crowded  with  traffic  there  is  this  objection  to  gutter- 
stones  of  uniform  width,  that  the  continuous  longitudinal 
joint  between  the  gutter  and  the  rest  of  the  pavement,  wears 
into  long,  deep  ruts,  or  grooves,  which  cause  severe  strains 


PAVEMENT  OF  STONE  BLOCKS. 


151 


upon  the  running  gear  of  vehicles,  when  the  wheels,  having 
once  entered  the  rut,  attempt  to  leave  it.  A remedy  for 
this  evil  would  seem  to  be  to  break  the  continuous  joint,  by 
making  the  gutter-stones  of  different  widths — say  12  inches 
and  15  inches  alternately,  as  shown  in  Pig.  47.  Pavements 
for  sidewalks  are  more  fully  described  in  Chapter  VI. 

Pavement  of  Stone  Blocks. 

Although  the  form  and  dimensions  of  paving  blocks  have 
been  the  subject  of  much  discussion,  all  authorities  agree 
that  the  material  should  possess  in  a superior  degree  the 
qualities  of  toughness  and  hardness,  so  that  it  shall  not 
crush,  nor  wear  away  too  rapidly,  under  the  effects  of  the 
traffic  conducted  upon  it.  It  is  also  very  desirable  that  the 
stones  shall  not  polish  and  become  slippery.  While  there 
may  be  considerable  variation  in  the  widths  and  lengths  of 
blocks  for  the  same  pavement,  they  should  be  of  uniform 
depth,  or  very  nearly  so,  if  the  foundation  be  other  than  a 
form  of  sand  or  gravel.  Were  it  otherwise  the  blocks  of 
least  depth  would  require  to  be  underpinned  at  considerable 
extra  cost,  either  with  good  mortar,  or  stone  chips  laid  in 
mortar,  in  order  to  bring  their  tops  to  the  required  height. 
If  a thick  joint  of  sand  alone  be  placed  between  them  and 
the  foundation,  they  will  subside  more  than  the  blocks  of 
proper  depth  which  surround  them,  under  which  the  layer  of 
sand  is  very  thin.  The  condition  therefore  that  the  blocks 
shall  settle  equally,  requires  them  to  be  of  uniform  depth. 

Hence,  for  pavements  laid  in  mortar,  the  blocks  should  be 
of  nearly  uniform  vertical  thickness.  As  each  stone  is  liable 
to  have  upon  it  the  entire  weight  of  the  load  carried  by  one 
wheel,  it  should  be  sufficiently  large  to  resist  crushing,  and 


152 


ROADS,  STREETS,  AND  PAVEMENTS. 


be  so  firmly  supported  underneath  as  to  resist  depression. 
In  the  direction  of  the  draught,  it  should  be  no  broader 
than  the  length  of  a horse’s  shoe,  say  not  exceeding  4,  01 
at  most  4^  inches,  in  order  that  the  joints  between  the  blocks 
may  give  a firm  foothold  at  each  step  without  slipping. 
Their  depth  in  a vertical  direction  should  be  a little  more 
than  double  their  horizontal  breadth,  in  order  that  they 
shall  not  tilt  up  on  one  side  when  a weight  comes  upon  the 
other.  For  the  same  reason,  and  to  increase  the  area  of 
bearing  surface  on  the  foundation,  their  length  across  the 
street,  should  be  at  least  equal  to  their  depth,  and  may 
advantageously  exceed  it  to  some  extent. 

The  most  desirable  dimensions  for  paving  blocks  are 


therefore  as  follows  : 3-J  to  4}  inches  broad  measured  along 
the  street ; 9 to  12  or  even  15  inches  long  measured  across  the 
street ; 8 to  10  inches  in  vertical  depth. 

The  stones  are  placed  closely  in  contact,  on  their  edge  in 


PAVEMENT  OF  STONE  BLOCKS. 


153 


continuous  courses,  with  their  largest  dimensions  either 
directly  across  the  street  as  in  Fig.  47,  or  at  an  angle  of  45° 
to  60°  with  its  axis.  It  is  claimed  that  the  latter  method 
is  preferable,  as  the  blocks  are  then  less  likely  to  wear  into 
a convex  form.  When  the  joints  run  crosswise,  the  edges 
of  the  cross-joints  receive  a more  severe  impact  from  the 
wheels  than  when  the  latter  cross  the  courses  diagonally. 

The  stones  of  the  same  course  must  be  of  the  same 
breadth,  the  broadest  edge  of  each  stone  being  placed  down, 
when  there  is  any  difference  in  this  respect.  The  joints  are 
then  close  below  and  open  on  top, 
and  should  be  compactly  filled  in  with 
sand  or  fine  gravel.  Granite  chips 
are  sometimes  wedged  in  between  the 
blocks.  Paving  blocks  generally  give 
joints  sufficiently  open  to  secure  a 
good  foothold  for  horses,  without 
rendering  special  care  necessary  to  fig.  48. 

attain  that  end.  When  placed  as  in  Fig.  47,  the  continuous 
joints  run  across  the  street  and  not  lengthwise  of  it. 

Upon  steep  streets  the  blocks  are  sometimes  arranged  in 
two  sets  of  diagonal  courses  meeting  in  the  middle  of  the 
roadway  in  an  angle  pointing  up  the  ascent,  as  shown  in  Fig. 
48.  The  joints,  by  sloping  downwards  to  the  right  and 
left,  aid  the  flow  of  surface  water  and  other  liquids  into 
the  side  gutters. 

If  the  foundation  be  concrete,  or  rubble  stone  filled  in 
with  concrete,  or  an  old  broken  stone,  cobble  stone,  or  rub- 
ble stone  covering,  in  good  condition,  it  would  be  advanta- 
geous, and  produce  in  many  respects  a better  pavement,  to 
7* 


L54 


HOADS,  STREETS,  AND  PAVEMENTS. 


set  each  stone  firmly  in  a bed  of  stiff,  though  not  very  rich, 
cement  mortar,  care  being  taken  not  to  disturb  it  again,  or 
allow  any  travel  upon  it,  until  the  mortar  has  had  some 
days  to  set  and  harden.  Some  constructors  recommend  the 
use  of  cement  mortar  in  the  joints  between  the  blocks.  The 
mortar  for  this  purpose  should  be  mixed  with  a small  quan- 
tity of  water — not  enough  to  make  it  plastic — and  should 
then  be  tamped  into  the  joints,  or  calked  in  after  the  method 
pursued  in  pointing  first-class  stone  masonry. 

The  joints  may  be  filled  with  bituminous  mastic,  or 
bituminous  limestone,  into  which  chips  of  granite  or  pieces 
of  hard  slate  are  compactly  driven  while  it  is  warm  and  soft. 

The  usual  method  however,  is  to  set  the  blocks  in  contact, 
and  then  to  spread  over  the  pavement  a layer  of  clean  sand, 
and  allow  it  to  work  gradually  into  the  joints.  The  sand 
however  absorbs  and  retains  the  filthy  surface  liquids. 

Sand  being  incompressible  when  in  a confined  state,  con- 
stitutes a good  filling,  with  the  objection  above  named,  espe- 
cially when  the  blocks  are  set  in  mortar,  as  it  then  has  no 
avenue  of  escape,  and  readily  adjusts  itself,  and  assumes  a 
new  condition  of  stable  equilibrium,  for  every  change  or 
disturbance  caused  by  the  vibrations  of  the  roadway. 

When  the  foundation  is  a form  of  sand  or  gravel,  or  very 
uneven  broken  stone,  or  rubble  stone,  requiring  a thick  layei 
of  sand  to  bring  the  surface  to  the  required  form,  the  pav- 
ing blocks  are  not  bedded  in  mortar,  but  are  generally  set 
in  place  upon  a layer  of  clean  sand  or  gravel  spread  upon  the 
foundation  to  receive  them.  As  the  work  progresses  each 
block  is  slightly  rammed,  and  when  an  area  several  yards 
square,  reaching  entirely  across  from  one  curb  to  the  other  has 
been  completed,  a heavy  wooden  rammer  weighing  50  to  60 


PAVEMENT  OF  STOifE  BLOCKS. 


155 


pounds  manned  by  two  men,  is  passed  over  them,  a number 
of  blows  being  given  to  each  block.  The  blocks  which  break 
must  be  replaced  by  others,  and  those  whose  tops  are  forced 
below  the  required  street  surface,  are  taken  up,  additional 
sand  filled  under  them,  and  then  reset.  A layer  of  clean  sand 
about  two  inches  deep  is  then  spread  over  the  pavement,  and 
allowed  to  work  its  way  gradually  in  between  the  blocks. 

When  the  foundation  is  only  a sand  or  gravel  form,  the 
paving  stones  should  be  somewhat  larger  in  horizontal  area 
than  if  intended  for  a concrete  or  broken  stone  foundation,  for 
the  reason  that  small  blocks,  and  more  especially  thin  blocks 
set  on  edge,  have  a tendency  to  settle  into  sand  unequally. 

Upon  streets  having  a longitudinal  inclination  exception- 
ally great,  special  precautions  may  very  properly  be  taken  to 
secure  a more  perfect  foothold  for  the  horses’  feet,  than 
would  be  afforded  by  rectangular  or  cubical  blocks  placed 
horizontally  with  close  joints. 

If  the  blocks  can  be  procured  of  marked  wedge  shape, 
without  extra  cost,  it  will  generally  suffice  to  set  them  with 
their  broadest  edge  down,  as  in  Fig.  49,  so  as  to  form  a 


Fig.  49. 


series  of  open  joints  across  the  street.  These  may  be  filled 
in,  to  within  about  one  inch  of  the  top,  with  granite  chips 
(irmly  driven  with  a hammer,  and  topped  off  with  a two- 
inch  layer  of  clean  sand.  Some  stone  can  be  split  readily 
into  these  forms. 

With  blocks  that  are  essentially  rectangular,  the  same 
end  may  be  gained  by  setting  the  transverse  courses  about 


156 


ROADS,  STREETS,  AND  PAVEMENTS. 


three-fourths  of  an  inch  apart,  and  interposing  a course  of 
slate  between  them  as  in  Fig.  50,  with  the  upper  edges  about 


Fig.  50. 

one  inch  below  the  street  surface,  finishing  the  work  with  a 
layer  of  sand  as  before,  or,  by  a simple  method,  the  stones 
may  be  set  slightly  canted  on  their  beds  so  as  to  lean  toward 
the  descent  as  in  Fig.  51,  thus  forming  a series  of  triangulai 


Fig.  51. 


ridges,  or  corrugations  across  the  street.  The  joints  are 
filled  in  with  clean  sand  in  the  usual  way. 

The  Guidet  Pavement. 

Broadway,  in  New  York  city,  below  Fourteenth  St.,  is 
covered  with  what  is  known  as  the  Guidet  pavement,  com 
posed  of  granite  blocks  as  shown  in  Fig.  47,  set  on  a foun 
dation  of  cement  concrete  6 inches  thick.  The  same  kind 
of  pavement  similarly  laid,  surrounds  the  New  York  posi 
office,  at  the  corner  of  Broadway  and  Park  Row. 

Upon  newly  made  earth,  or  in  wet,  springy  or  swampy 
soils,  the  foundation  should  always  be  a layer  of  good 
concrete,  at  least  6 inches  thick,  laid  upon  a bed  formed  par- 
allel to  the  finished  street  surface.  The  stones  are  then  set 
in  a layer  of  clean  sand  spread  over  the  concrete  to  a depth 
of  half  an  inch  to  an  inch.  The  left  hand  portion  of  Fig. 


THE  GUIDET  PAVEMENT. 


15? 


47  shows  this  pavement.  The  usual  specifications  for  the 
Guidet  paving  blocks  require  that  they  shall  be  of  granite, 
equal  in  hardness  to  the  Quincy  granite,  of  durable  and  uni- 
form quality,  each  measuring  not  less  than  3-J-,  nor  more  than 
4|-  inches  in  width,  on  the  upper  surface  or  face,  and  not  less 
than  10  nor  more  than  15  inches  in  length,  and  not  less  than 
8 nor  more  than  9 inches  in  depth.  Blocks  of  3^-  inches  in 
width  on  the  face,  to  be  not  less  than  3 inches  in  width  at 
the  base  ; all  other  blocks  to  measure  on  the  base  not  more 
than  1 inch  less  in  width  or  in  length  than  on  the  face. 
The  blocks  are  set  upright  in  close  contact  on  their  edges,  in 
courses,  with  the  longest  dimensions  and  the  continuous 
joints  running  across  the  street,  breaking  joints  lengthwise 
of  the  street.  The  ends  of  the  blocks  are  dressed  off  so  as  to 
give  close  joints  in  the  direction  of  the  draught,  while  the 
broad  vertical  sides  of  the  blocks  are  left  rugged  or  uneven, 
or  with  the  split  rock-face,  so  that  the  continuous  joints 
running  across  the  street  are  somewhat  open.  This  pave- 
ment, besides  being  firm,  strong  and  durable,  offers  a good 
foothold  for  horses,  in  its  open  cross-joints,  and  an  easy 
draught  for  loaded  vehicles  in  the  narrowness  of  the  blocks. 
It  gives  very  general  satisfaction  in  New  York,  and  seems 
well  adapted  to  a street  subjected  to  very  heavy  traffic.  It 
would  be  an  improvement,  with  a concrete  foundation,  to 
set  the  blocks  in  cement  mortar,  as  a security  against  unequal 
settlement.  It  requires  from  24  to  25  of  these  blocks  to  lay 
one  square  yard.  Their  cost,  exclusive  of  land  haulage  from 
the  dock  to  the  street  where  they  are  to  be  used,  varies  with 
the  price  of  labor,  from  12  to  15  cents  each,  after  allowing 
for  loss  and  breakage.  The  cost  of  a sand  foundation  in 
large  cities  generally  comprises  excavating  and  rolling  the 


158 


ROADS,  STREETS,  AND  PAVEMENTS. 


road  bed,  hauling  away  the  excavated  material,  and  purchas- 
ing, transporting,  filling  in,  and  rolling  the  sand,  and  will 
therefore,  vary  with  the  price  of  labor  and  sand,  and  the 
length  of  haulage.  In  the  city  of  New  York  a sand  form  9 
to  12  inches  thick,  will  cost,  when  ready  for  the  pavement, 
from  40  to  60  cents  per  square^yard. 

A good  cement  concrete  foundation  6 inches  thick,  exclu- 
sive of  excavating  and  compacting  the  road  bed  and  removing 
the  materials,  will  cost  from  11.40  to  $1.50  per  square  yard. 

At  the  present  time,  (autumn  of  1875)  contracts  could  be 
let  in  New  York  city,  for  the  Guidet  pavement  on  a sand  foun- 
dation 6 to  8 inches  thick,  for  from  $4.75  to  $5.25  per  square 
yard.  This  includes  a very  liberal  profit  to  the  contractor. 

In  some  localities,  cubes  of  eight  inches  are  preferred  for 
paving.  Their  cost,  delivered  upon  the  streets  in  our  east- 
ern city,  will  generally  not  exceed  $2.75  to  $3.00  per  square 
yard  of  surface.  When  laid  upon  a form  of  sand  or  gravel, 
9 to  12  inches  deep,  it  will  cost  at  least  50  cents  more  per 
square  yard  to  make  the  foundation  and  lay  the  stone,  bring- 
ing the  total  cost  of  the  finished  pavement  to  $3.25  to  $3.50 
per  square  yard. 


The  Russ  Pavement. 

Several  years  ago,  a portion  of  Broadway,  New  York,  was 
covered  with  the  Russ  pavement  at  a cost  of  $5.50  per  square 
yard.  The  natural  soil  at  the  level  of  this  road  bed  was 
sand  slightly  mixed  with  clay.  This  was  excavated  to  a 
depth  of  17  inches,  and  then  a layer  of  granite  chips,  from 
4 to  8 inches  in  largest  dimensions,  and  about  half  that  thick- 
ness, was  laid  upon  the  bed  and  rammed  down  nearly  flush 
with  the  graded  surface.  Upon  this  was  placed  a foundation 


THE  RUSS  PAVEMENT. 


159 


of  concrete,  six  to  seven  inches  thick,  formed  in  detached 
rectangular  sections,  and  composed  of  1 volume  of  Kosendale 
cement,  2-J  volumes  of  clean  coarse  sand,  2\  of  broken  stone 
like  the  Macadam  road  metal,  and  2 of  coarse  gravel.  The 
paving  stones  were  rectangular  blocks  of  sienitic  granite,  10 
inches  deep,  10  to  18  long,  and  5 to  12  wide,  set  in  courses 
at  an  angle  of  45°  with  the  axis  of  the  street,  and  so 
arranged  that  the  pavement  could  be  taken  up  in  rectangular 
sections  of  4ft.  by  3^ft.  in  order  to  reach  the  gas  and  water 
pipes,  without  disturbing  the  adjacent  portions. 

This  pavement  did  not  give  entire  satisfaction,  the  sur- 
face of  the  blocks  being  too  broad  to  give  a good  foothold 
for  the  horses.  They  also  became  smooth,  polished,  and 
slippery.  It  was  therefore  replaced  by  the  Guidet  pavement 
already  described.* 

* The  following  is  condensed  from  the  specifications  in  the  patent 
granted  to  Mr.  Russ,  in  1846. 

First.  The  sub-soil  is  graded. 

Second.  Granite  chips,  etc.,  4 to  8 inches  in  diameter,  and  about 
half  as  thick,  are  laid  on  the  road  bed  with  the  flattest  sides  upward, 
and  rammed  flush  with  the  grading. 

Third.  A concrete  foundation  8 to  10  inches  thick  is  then  laid  in 
frames  of  sound  wood,  cast  iron,  iron  stone  pottery,  burnt  earth  or 
any  other  fit  material,  thicker  at  bottom  than  at  top.  Before  the  con- 
crete is  put  in,  bars  of  iron  are  placed  into  the  panels,  crosswise,  with 
holes  in  them,  through  which  they  are  united  by  an  eyebolt,  with  a 
ring  in  the  head  of  each  bolt.  Large  panels  receive  2 or  more  sets 
of  such  bars,  bolts  and  rings.  The  concrete  is  then  filled  in  and  con 
solidated,  after  which  it  may  be  lifted  out  of  any  panel  to  obtain 
access  to  sewers,  gas  or  water  pipes,  etc. 

Fourth.  The  pavement  consists  of  granite  or  sienite  blocks 
averaging  10  to  12  inches  long,  4 to  5 inches  wide  on  the  top  surface, 
and  about  10  inches  deep,  carefully  laid,  the  ranges  of  stones  forming 


160 


ROADS,  STREETS,  AND  PAVEMENTS. 


The  Belgian  Pavement. 

The  Belgian  pavement,  so  named  from  its  common  use 
in  Belgium,  is  made  with  blocks  of  stone  that  are  nearly 
cubical  in  form,  split  as  nearly  as  possible  to  square  angles, 
with  little  if  any  dressing.  The  trap  rock,  which  forms  the 
palisades  of  the  Hudson  river,  is  extensively  used  for  this 
purpose. 

The  following  is  one  of  the  common  forms  of  specification 
for  this  pavement ; each  block  to  measure  on  the  face  or 
upper  surface  not  less  than  five  inches  nor  more  than  seven 
inches  in  length  ; nor  less  than  five  inches  nor  more  than  six 
inches  in  breadth ; in  depth  not  less  than  six  inches  nor 
more  than  seven  inches  ; nor  shall  the  difference  between 
the  base  and  the  top  surface  of  any  stone  exceed  one  inch  in 
either  direction. 

The  sub-soil  or  other  matter,  other  than  clean  sand,  is  to 

lozenge- shaped  divisions,  presenting  the  edges  diagonally  to  the 
wheel  tires.  The  stone  over  the  centre  of  each  panel  is  to  have  2 
holes  for  a lewis,  that  it  may  be  lifted  out  for  a commencement  of 
removing  the  stones  to  get  access  to  the  panel  below.  This  stone 
should  be  set  only  in  dean  sand  ; all  the  rest  of  the  stones  are  cov- 
ered with  sand  that  must  be  well  washed  into  the  joints,  and  there 
consolidated  by  thin  grouting  of  hydraulic  cement  run  freely  into 
the  sand  and  left  to  harden  between  the  stones. 

Fifth.  I do  claim  as  new  and  of  my  own  invention  the  constructing 
a concrete  foundation  in  panels  or  sections  (to  give  access  to  pipes 
or  conduits  below)  by  the  application  and  combination  therewith  of 
frames  formed  of  any  suitable  material,  with  a thinner  edge  upward 
to  allow  the  concrete  mass  to  be  lifted  out  when  needed,  substantially 
as  described,  when  this  is  combined  with  a paved  road- way  of  any 
hind  laid  thereon  as  described. 


BELGIAN  PAVEMENT. 


161 


be  excavated  and  removed  to  a depth  of  thirteen  inches  beloM 
the  top  surface  of  the  new  pavement  when  fully  rammed, 
forming  the  proper  arch  or  grade  beneath  the  proposed  pave- 
ment. Upon  this  foundation,  clean,  coarse  sand  or  gravel 
is  to  be  filled  and  thoroughly  compacted  by  ramming  or 
rolling  to  the  proper  depth  to  receive  the  paving  stones, 
which  are  then  to  be  laid  in  close  contact,  in  even  courses, 
transversely  to  the  line  of  the  street.  When  so  laid,  the 
pavement  shall  be  thoroughly  rammed  to  the  grade  and  to 
the  proper  arch  or  crown,  after  which  the  surface  is  to  be 
covered  with  one  inch  in  depth  of  clean,  coarse  sand,  and  all 
interstices  filled  in  solid  with  sand. 

The  blocks  shall  not  be  laid  more  than  fifteen  feet  in 
advance  of  the  rammers.  When  the  road  bed  is  not  of  firm 
and  compact  soil,  the  thickness  of  the  sand  foundation  must 
be  increased  to  10  or  12  inches  or  more,  and  in  soft,  com- 
pressible, or  swampy  soils  a concrete  foundation  should  be 
resorted  to.  Indeed  a solid  and  unyielding  foundation  is 
more  necessary  under  a Belgian  pavement,  than  under  the 
larger  blocks  used  in  the  Russ  and  Guidet  methods. 

The  market  price  of  Belgian  paving  blocks,  whether  of 
trap  rock  or  granite,  fluctuates  with  the  price  of  labor,  from 
$35  to  $60  per  thousand  in  New  York  city ; so  that  the 
cost  of  the  finished  pavement  laid  upon  six  inches  of  con- 
crete, will  vary  from  about  $3.60  to  $4.50  per  square  yard, 
exclusive  of  profit  to  the  contractor. 

In  setting  the  stones  in  a sand  form  it  is  important  that 
they  should  all  receive  an  equal  amount  of  ramming,  to  pre- 
vent unequal  settlement  subsequently  ; and,  if  set  in  mortar 
on  a concrete,  rubble,  or  cobble  foundation,  they  should  not 
be  walked  upon  or  otherwise  disturbed  for  some  hours  after 


102 


HOADS,  STREETS,  AND  PAVEMENTS. 


they  have  been  settled  to  their  place,  so  that  the  mortar  will 
have  time  to  set,  and  the  street  should  not  be  opened  to 
traffic  for  some  days,  or  until  the  mortar  has  attained  suf- 
ficient strength  to  resist  crushing. 

Wooden  Pavements. 

Wooden  pavements  made  with  blocks  of  wood — generally 
yellow  or  white  pine — set  on  the  end  of  the  grain,  although 
they  have  been  extensively  tried  in  the  United  States  and 
elsewhere,  within  the  last  fifteen  years,  are  unfit  for  streets 
subjected  to  heavy  traffic.  They  are  slippery  in  wet  weather, 
and  are  of  course  very  perishable,  from  their  inability  to 
resist  either  the  wear  and  tear  of  traffic,  or  the  course  of 
ordinary  decay.  Various  devices  have  been  resorted  to  in 
order  to  lessen  these  objections  and  render  these  pavements 
safe  and  reasonably  durable,  such  as  setting  them  with  wide 
open  joints  across  the  street  so  as  to  give  the  horses  a good 
foothold ; Kyanizing,  Burnettizing  or  creosoting  the  wood 
to  prevent  decay  ; and  underlaying  them  with  an  elastic 
foundation  of  boards  or  planks,  to  enable  the  blocks  to  resist 
the  crushing  and  wearing  effects  of  heavily  loaded  vehicles.* 

* One  of  the  most  efficacious  methods  of  preserving  wood  from 
decay,  as  well  as  from  the  attacks  of  land  and  marine  insects,  consists 
in  impregnating  it,  by  either  the  Betliell  or  the  Seely  process  with  the 
dead  oil — containing  carbolic  acid  (Ci2  H6  0.2)  or  cresylic  acid  (Ci4  H 
02)  obtained  in  the  distillation  of  coal  tar.  “ By  the  Bethell  process 
the  timber  is  placed  in  an  air  tight  cylinder  of  boiler  iron,  which  is 
then  exhausted  of  air  to  the  point  indicated  by  20°  on  the  Bourdon 
vacuum  gauge.  At  this  point  the  creosote  is  admitted  into  the  cyl- 
inder at  a temperature  of  about  120°  Fall.,  at  once  filling  it  to  within 
an  inch  or  two  of  the  top.  A pressure  of  about  150  pounds  per  squaro 
inch  is  then  applied,  and  maintained  for  from  five  to  eight  hours, 


tfICObSO#  lavement* 


163 


The  usual  sizes  for  the  wooden  blocks  are  from  3 to  4 
inches  in  width,  8 to  14  inches  in  length  across  the  street, 
and  6 to  8 inches  in  depth. 

The  ordinary  requirements  for  the  Nicolson  pavement 
are  that  the  block  shall  be  of  sound  yellow  or  white  pine,  free 
from  sap,  of  rectangular  form,  and  not  less  than  3 nor 
more  than  4 inches  wide,  not  less  than  6 nor  more  than  14 
inches  long,  and  6 inches  deep,  the  grain  of  the  wood  being 
in  the  direction  of  the  depth.  The  blocks  for  paving  the 
side  gutters  are  to  be  sawed  to  a bevel,  so  as  to  form  a suita- 
ble channel  way  of  uniform  cross  section  about  six  inches 
outside  the  line  of  curb-stones,  to  carry  off  the  surface  water. 

In  preparing  the  foundation,  the  subsoil  and  all  material 
other  than  clean  sand,  is  excavated  to  a depth  of  9 inches 
below  the  top  surface  of  the  new  pavement,  and  parallel  there- 
to. Upon  this  road-bed  clean  sand  is  filled  in  to  the  required 

depending  on  the  size  of  the  pieces  of  timber  under  treatment.  The 
creosote  oil  is  then  drawn  off  and  the  timber  removed.” 

The  Seely  process,  in  brief,  consists  (1)  in  subjecting  the  wood  to  a 
temperature  above  the  boiling  point  of  water,  and  below  300°  Fab., 
while  immersed  in  a bath  of  creosote  oil,  for  a sufficient  length  of 
time  to  expel  the  moisture.  When  the  water  is  thus  expelled  the 
pores  contain  only  steam  ; and  then  (2)  the  hot  oil  is  quickly  replaced 
by  a bath  of  cold  oil,  by  means  of  which  change  the  steam  in  the 
pores  of  the  wood  is  condensed,  and  a vacuum  formed  into  which  the 
oil  is  forced  by  atmospheric  pressure  and  capillary  attraction.  The 
dead  oil  referred  to  above  contains  only  a small  percentage  of  the  two 
acids  named.  It  is  claimed  that  either  of  them  applied  in  a pure  una- 
dulterated state  to  the  surface  of  a piece  of  timber,  like  a paint, 
will  thoroughly  permeate  the  entire  piece,  even  if  it  be  one  foot  oi 
more  in  thickness,  and  will  effectually  prevent  decay,  a question 
which  has  not  yet  been  satisfactorily  determined.  The  process  ia 
now  on  trial. 


164 


ROADS,  STREETS,  AND  PAVEMENTS. 


depth  and  a close  flooring  of  common  pine  boards  1 inch 
thick  is  laid  thereon,  lengthwise  with  the  line  of  the  street, 
the  ends  resting  on  similar  boards  laid  transversely  from 
curb  to  curb.  The  flooring  boards  are  thoroughly  tarred  on 
both  sides  with  hot  coal  tar,  brought  to  a proper  consistency 
by  boiling  with  pitch,  so  as  to  be  tough  and  not  brittle  when 
cool. 

Upon  this  flooring  the  blocks  are  set  on  end  in  parallel 
courses  running  across  the  street,  the  lower  end  of  each 
block  having  been  previously  dipped  to  half  its  height  in 
hot  coal  tar  prepared  as  above  directed.  The  joints  which 
run  parallel  with  the  line  of  street  are  close,  and  not  con- 
tinuous. 

The  transverse  courses  are  separated  from  each  other  f of 
an  inch,  by  batons  of  common  pine  one  inch  wide  and  f of 
an  inch  thick,  laid  end  to  end  at  the  base  of  the  blocks,  the 
whole  being  secured  and  made  firm  by  nails  driven  through 
each  baton  and  block  with  the  flooring  boards. 

The  spaces  above  the  batons  between  the  courses  of 
blocks  is  then  filled  with  a kind  of  concrete  composed  of 
clean  roofing  gravel  and  hot  coal  tar,  thoroughly  mixed  and 
compactly  rammed  in  with  suitable  iron-shod  rammers. 

Finally  the  surface  of  the  pavement,  as  fast  as  it  is  fin- 
ished, is  thoroughly  coated  with  hot  coal  tar,  prepared  as 
specified,  and  immediately  covered  with  fine  sand  and  gravel, 
mixed  in  equal  proportions  and  laid  on  not  less  than  one 
inch  in  thickness. 

A section  of  this  pavement  taken  parallel  to  the  line  of 
street  is  shown  in  Fig.  52. 

A modification  of  this  method  consists  in  making  the 
blocks  square  and  all  of  the  same  dimensions  on  top  (about 


STONE  PAVEMENT. 


165 


4 in.  by  4 in.),  one  half  of  them  being  3 or  4 inches  less  in 
depth  than  the  rest,  and  then  setting  them  on  the  prepared 
foundation  in  continuous  courses  closely  in  contact  both 
across  and  lengthwise  of  the  street,  alternating  the  deep  and 
shallow  blocks  with  each  other  in  both  directions,  thus 
forming  a series  of  cells  about  4 inches  square  and  3 to  4 


Fig.  52. 


inches  deep,  arrayed  like  the  dark  squares  on  a chess  board. 
Fig.  53.  These  cells  are  filled  with  coarse  gravel  and  pre- 
pared coal  tar  or  asphaltum,  and  the  whole  pavement  is 
coated  over  with  the  coal  tar  preparation  and  a layer  of  fine 
sand.  When  the  flooring  of  boards  is  omitted,  it  is  some- 
times the  practice  to  underlie  the  block  with  a coat  of  lime 


Fie.  58. 


or  cement  mortar,  or  with  a layer  of  thick  paper  covered  with 
coal  tar,  in  order  to  exclude  the  moisture  from  below. 

By  the  Stowe  method  the  blocks  rest  directly  upon  a form 
of  clean  well  compacted  sand  or  gravel,  which  may  be  from 


lC6  ROADS,  STREETS,  AND  PAVEMENTS. 

4 to  6 inches  in  thickness  only,  if  the  road  bed  be  hard  and 
firm. 

In  soft  spongy  or  clayey  soils  the  sand  foundation  should 
be  of  greater  thickness,  though  seldom  exceeding  8 to  10 
inches.  The  sand  foundation  should  be  carefully  graded  so 
as  to  be  parallel  to  the  finished  street  surface. 

The  blocks  are  set  in  courses  transversely  across  the  street 


Fig.  54. 


so  as  to  break  joints  lengthwise  of  the  street,  the  courses 
being  separated  from  each  other  one  inch,  by  a continuous 
course  of  wooden  wedges  placed  close  together  edge  to  edge, 
and  extending  from  curb  to  curb.  These  wedges  are  set  in 
the  first  instance  with  their  tops  flush  with  the  top  surface 
of  the  blocks.  After  the  whole  pavement  shall  have  been 
well  rammed  so  as  to  give  each  block  a firm  bed,  the  wedges 
are  driven  down  about  3 inches,  and  the  open  joints  thus 
formed  above  them  between  the  courses  are  filled  in  with  a 
concrete  composed  of  hot  coal  tar  and  fine  roofing  sand  and 
gravel.  (See  Fig.  54.)  The  surface  of  the  pavement  may 
then  be  coated  with  coal  tar  prepared  by  boiling  with  pitch, 
and  finished  off  with  a thin  layer  of  sand. 

A modification  of  this  general  method  of  forming  the 
pavement  by  setting  single  blocks  of  wood  in  courses  slight- 
ly separated  from  each  other,  has  been  practiced  to  some 
extent  without  very  satisfactory  results.  It  consists  in  form- 
ing the  blocks  into  sections  or  compound  blocks,  each  con- 
taining from  12  to  15  single  blocks  breaking  joints  with 
each  other  in  one  direction,  and  held  together  with  wooden 


OTHER  WOODEN  PAVEMENTS. 


1 6? 


tree-nails,  passing  entirely  through  the  section  from  side  to 
side,  and  striking  each  full  block  twice.  Each  section  has 
a triangular  groove  running  horizontally  around  its  four 
sides,  for  the  reception  of  strong  wooden  keys.  The  sections 
are  set  in  contact,  breaking  joints,  upon  a foundation  of  sand 
or  a flooring  of  boards,  and  thus  mutually  support  each 
other  and  are  prevented  from  tilting  by  the  keys  inserted 
horizontally  between  them. 


Deep  grooves  are  cut  in  the  upper  face  of  each  section 
so  as  to  form  continuous  grooves  across  the  finished  pave- 
ment. These  are  filled  with  cement  concrete,  a mixture  of 
coal-tar,  sand  and  gravel,  or  other  suitable  material.  Their 
principal  object  is  to  give  a secure  foothold  for  draught 
animals.  One  of  the  compound  blocks  is  shown  in  Fig.  55. 
They  are  brought  upon  the  street  in  readiness  for  laying. 

Another  method  is  to  set  the  blocks  on  a base  of  cast- 
iron  formed  into  cells  on  top,  into  which  the  blocks,  pre- 
viously dipped  in  hot  asphaltum,  or  otherwise  properly  pre- 
pared, are  inserted  to  about  half  their  depth,  each  block 
having  a shoulder  around  it  which  bears  upon  the  top  of  the 
iron  partition  separating  the  cells. 


166 


ROADS,  STREETS,  AND  PAVEMENTS. 


The  cast-iron  base  is  formed  in  sections,  of  convenient 
area  for  removal  in  places  where  necessary,  each  section 
being  screwed  to  those  adjacent  to  it  by  iron  clamps  or  sta- 
ples as  seen  in  Fig.  56  at  a , and  by  pins  as  seen  at  b ; or  they 
may  be  held  together  by  dove-tail  projections  fitting  into 
corresponding  recesses.  The  blocks  fit  together  so  as  to 
form  close  joints  on  top,  a channel  being  entin  each,  so  as 


Fig.  56. 


to  form  continuous  channels,  across  the  street,  to  give  the 
horses  a foothold.  All  the  blocks  are  brought  to  the  re- 
quired form  by  machinery.* 

* The  author  is  indebted  to  E.  S.  Cliesbrough,  Esq.,  City  Engineer 
of  the  city  of  Chicago,  for  the  following  interesting  report  on  the 
wooden  pavements  in  that  city  : 

“ It  is  true  that  wooden  pavements  have  been  more  successful  here 
than  in  any  other  important  city.  The  reason  is  owing  far  more,  I 
think,  to  local  circumstances  than  to  any  peculiarity  in  the  kinds  of 
pavements  used.  Our  city  is  on  a very  fiat  site,  underlaid  by  a moist 
soil.  Our  streets  are  generally  wide,  and  our  traffic,  instead  of  being 
principally  on  two  or  three  main  thoroughfares,  is  greatly  diffused 
When  it  is  added  we  have  the  cheapest  important  lumber  market  in 
the  country,  you  can  easily  see  why  wooden  pavements  should  be 
more  favored  with  us  than  they  are  elsewhere.  Besides  these  cor 


BRICK  PAVEMENT. 


1G9 


Brick  Pavements. 

Among  the  many  attempts  that  have  been  made  to  com- 
bine bitumen  and  other  hydro-carbons,  including  even  ordi- 
nary coal  tar,  with  other  substances  for  street  pavements, 
the  hydro-carbonized  brick  pavement  introduced  by  Messrs. 

siderations  I should  mention  that  our  wooden  pavements,  while  in 
good  condition,  are  much  more  agreeable  to  drive  over,  than  any  other 
kind  it  is  practicable  to  put  down  here,  except  the  asphalt,  which  is 
much  more  costly. 

“ As  the  property  holders  on  each  side  of  a street  are  assessed  the 
cost  of  paving  it,  except  at  intersections  with  other  streets,  it  is  very 
natural  they  should  have  something  to  say  with  regard  to  the  kind  of 
pavement  to  be  put  down  ; in  fact  the  City  Council  has  of  late  allowed 
them  to  make  private  contracts,  the  work  however  to  be  subject  to  the 
supervision  of  the  Board  of  Public  Works.  As  a consequence  of  this 
state  of  things,  and  also  of  the  rival  claims  of  patentees,  we  have  tried 
various  kinds  of  pavement  during  the  last  twenty  years;  no  kind  has 
lasted  any  better  than  the  Nicolson.  There  has  not  been  time  enough 
yet  to  determine  whether  some  of  the  newer  kinds  will  last  as  long  or  not. 

“Of  the  kinds  of  pavement  laid  here  the  following  includes  all  it 
would  be  of  any  practical  value  to  describe,  viz.  : 

“ 1st.  The  Nicolson,  which  you  are  familiar  with. 

“2d.  Bastard  Nicolson,  differing  from  the  real  in  the  absence  ol 
wooden  strips  in  the  bottom  of  the  joints  between  the  blocks,  which  are 
filled  with  gravel. 

“ 3d.  The  Stowe,  which  is  without  any  flooring  under  the  blocks. 
These  are  kept  apart  with  thin  pieces  of  wood,  wedge-shaped  at  the 
end,  and  driven  into  the  sand  below.  The  upper  parts  of  the  joints 
between  the  blocKs  are  filled  like  those  of  the  Nicolson. 

“4th.  Tlie  (ireeley,  which  differs  from  the  Nicolson  simply  in  tne 
joint  between  the  blocks,  which  is  filled  entirely  \Vith  the  wooden 
strips,  leaving  no  room  for  gravel. 

44  5th.  The  unpatented,  which  is  without  flooring  under  the  blocks* 


170 


ROADS,  STREETS,  AND  PAVEMENTS. 


Cud  lie  uud  De  Valins,  of  San  Fancisco,  California,  deserves 
notice.  The  bricks  are  prepared  by  heating  them  in  a 
boiler-iron  tank  set  in  brick  work  with  a furnace  underneath, 
and  containing  a sufficient  quantity  of  the  liquid  hydro-car- 
bon to  allow  for  evaporation,  and  secure  a thorough  satura- 

lias  no  strips  between  them,  and  dispenses  with  tar.  It  is  the  most 
used  here  now. 

“ Some  portions  of  wooden  pavements  here  have  lasted  in  tolerably 
good  condition  for  nine  years.  When  properly  laid  on  wide  streets 
they  may  be  relied  upon  to  keep  in  good  condition  about  seven  years 
but  some  fail  in  less  time,  especially  where  there  is  much  traffic  and 
vehicles  are  compelled  to  go  in  ruts,  as  for  instance,  through  the  nar- 
row arch -ways  of  our  river  tunnels,  in  which  the  wooden  pavements 
keep  in  good  order  only  two  or  three  years.  The  traffic  through  these 
is  n >t  to  be  compared  with  that  on  Broadway,  or  Fulton  St.,  New  York. 

“Gravel,  Macadam,  Cobble,  and  Limestone  block  pavements  have 
all  been  used  here,  but  none  of  them  compare  favorably  with  the  best 
of  similar  kinds  used  in  eastern  cities.  The  cobble  has  been  entirely 
discontinued.  The  Macadam  is  but  little  used.  The  stone  is  very  dis- 
agreeable as  compared  with  wood,  and  no  new  streets  have  been  paved 
with  it  for  years.  The  first  wooden  pavements  of  this  city  were  laid 
in  1856. 

“ Our  streets  are  under  the  care  of  the  Superintendent  of  Public 
Works.  Mr.  I.  K.  Thompson,  the  former  one,  now  a member  of  the 
Board,  and  Mr.  Geo.  W.  Wilson,  the  present  one,  have  kindly  given 
me  their  views  on  this  subject.  They  are  both  satisfied  that  the  reason 
some  wooden  pavements  last  so  much  shorter  time  than  others,  is 
owing  to  a less  degree  of  care  or  skill,  in  the  selection  of  the  blocks. 
This  is  of  course,  when  they  are  subjected  to  like  usage.  They  also 
think  white  oak  is  more  durable  than  pine  used  in  this  way.  The 
unpatented  costs  about  $1.40  per  square  yard,  including  4 inches  of 
ballast  blocks  8 inches  in  depth.  The  blocks  are  now  laid  diag- 
onally across  the  streets,  and  are  considered  more  durable  laid  this 
way.” 


RRICK  PAVEMENT. 


171 


tion  of  the  bricks.  The  heat  is  applied  with  an  intensity 
and  duration  sufficient  to  reduce  the  liquid  material  to  a 
consistency  that  will  withstand  high  atmospheric  tempera- 
tures without  softening.  A tank  12ft.  long,  4 to  5ft.  wide, 
and  3ft.  deep  is  a suitable  size,  and  the  time  required  for  a 
thorough  saturation  of  the  bricks  about  24  hours.  It  is 
claimed  that,  thus  treated,  the  bricks  will  sustain  great 
weight  without  crushing,  and  will  resist  abrasion  and  wear 
when  subjected  to  ordinary  street  traffic,  but  no  satisfactory 
evidence  on  these  points,  based  up-on  their  practical  use,  has 
been  obtained.  The  description  furnished  by  the  inventors 
does  not  specify  the  kind  of  hydro-carbon  required  to  give 
the  best  results. 

The  prepared  bricks  are  set  in  a layer  of  sand  about  2 
inches  thick,  spread  upon  the  road  bed  after  the  latter  has 
been  properly  adjusted  to  a surface  parallel  with  that  of  the 
finished  pavement.  The  road  bed  and  sand  should  be  thor- 
oughly compacted  by  ramming  or  rolling. 

The  bricks  may  be  set  in  a single  layer,  on  edge  or  on 
end,  with  continuous  joints  running  across  the  street,  and 
breaking  joints  in  the  other  direction.  They  are  firmly  set- 
tled to  their  places  by  ramming,  and  hot  coal-tar  or  asphaltum 
is  poured  into  the  joints  to  cement  them  together,  and  ren- 
der the  pavement  impervious  to  water.  The  surface  is  fin- 
ished with  a coating  of  the  same  material  laid  on  hot,  and 
then  top-dressed  with  a layer  of  fine  gravel  or  coarse  sand. 
When  two  layers  are  used,  the  bottom  one  may  be  of  unpre- 
pared bricks  laid  flatwise,  with  the  joints  filled  in  with  sand, 
and  then  covered  with  a coat  of  hot  coal-tar  or  asphaltum. 
The  top  layer  may  be  set  on  edge  or  on  end,  and  finished' off 
as  in  the  case  of  a single  layer. 


172 


ROADS,  STREETS,  AND  PAVEMENTS. 


On  steep  grade  the  surface  layer  may  be  set  with  open 
half-inch  joints  running  across  the  street,  filled  in  with  a 
mixture  of  hot  tar  and  gravel. 

The  durability  of  this  pavement  has  yet  to  be  proved. 

Asphalt  Pavements. 

Within  the  last  twenty-five  years  bitumen,  in  some  of  its 
many  forms,  has  been  employed  to  a considerable  extent,  as 
the  binding  material  or  matrix  for  road  and  street  coverings 
laid  in  continuous  sheets  without  joints.  They  are  all  com- 
prised under  the  general  head  of  asphalt  pavements.  The 
city  of  Paris  took  the  lead  in  this  innovation  upon  the 
former  methods  of  paving  with  stone,  the  reasons  assigned 
for  the  change  being,  (1)  the  want  of  connection  and  homo- 
geneity, in  the  elements  of  which  the  stone  paving  is  com- 
posed, (2)  the  incessant  noise  produced  by  them,  (3)  the 
imperfect  surface  drainage  which  they  secure,  by  reason  of 
which  the  foul  waters  are  not  carried  off  but  filter  into  the 
joints,  and  (4)  the  ease  with  which  they  can  be  displaced, 
and  used  for  the  construction  of  barricades,  breastworks  and 
rifle  pits  in  time  of  civil  war. 

Varieties  of  Bitumen. 

There  are  several  varieties  of  bitumen  which  pass  insen- 
sibly into  each  other,  from  naphtha  the  most  fluid,  to  petro- 
leum and  mineral  tar , which  are  less  so,  thence  to  maltha 
which  is  more  or  less  cohesive,  and  thence  to  asphaltum 
which  is  generally  solid.  The  softer  kinds  gradually  harden 
in  time  by  the  evaporation  of  the  volatile  parts. 

They  are  hydro-carbons,  accompanied  in  the  solid  and 
viscous  kinds  with  various  oxygenated  carburets  of  hydrogen. 


THE  BITUMENS. 


1?3 


The  fluid  varieties  are  generally  solvents,  to  a greater  or  less 
extent,  of  those  that  are  solid  or  less  fluid. 

The  forms  of  bitumen  most  extensively  employed  for 
pavements  are  mineral  tar  ; asphalt  rock , which  is  an  amor- 
phous carbonate  of  lime  impregnated  with  mineral  tar,  and 
known  in  commerce  as  bituminous  limestone ; asphaltum  j 
heavy  petroleum  oils  like  those  from  West  Virginia,  or  others 
not  volatile  under  212°  Fah.,  or  the  residuum  of  refined 
petroleurp  containing  no  water,  and  so  refined  as  not  to  be 
volatile  at  212°  Fah. 


Mineral  Tar. 

The  principal  sources  of  the  natural  mineral  tar  of  corn- 
merce  are  in  France,  at  Bastenne  (Landes)  and  at  Pyrimont 
Seyssel  (Ain),  and  in  Switzerland  at  Val  de  Travers,  in  the 
canton  of  Neuchatel.  At  Bastenne  as  well  as  at  Gaujac,  in 
the  south  of  France,  it  flows  from  several  springs  mixed 
with  water.  The  Bastenne  mines  are  nearly  exhausted,  and 
no  shipments  of  mineral  tar  to  foreign  ports  are  now  made 
from  that  locality.  This  tar  is  also  found  impregnating 
quartzy  sandstone,  from  which  it  is  separated  by  boiling. 
At  Seyssel  both  sandstone  and  limestone  are  impregnated 
with  it.  By  boiling  the  sandstone  in  water  the  tar  rises  to 
the  surface,  or  adheres  to  the  sides  of  the  vessel.  The  sand- 
stone seldom  yields  more  than  10  per  cent  of  tar,  the  aver- 
age of  the  mines  falling  considerably  below  that  proportion, 
it  the  ordinary  temperature  mineral  tar  should  not  be 
cither  brittle  or  liquid,  but  viscous  and  ductile,  so  that  it 
will  freely  elongate  into  threads  when  drawn  out,  and  not 
break  unless  drawn  very  thin. 


174 


ROADS,  STREETS,  A HD  PAVEMENTS. 


Bituminous  Limestone. 

This  limestone,  known  also  as  asphalt  rock , occurs  in 
both  Seyssel  and  Yal  de  Travers.  The  stone  is  of  a liver 
brown  color,  irregular  in  fracture,  massive,  and  has  a specif- 
ic gravity  of  2.114,  water  being  1.000.  It  contains  from  5 
to  15  percent,  and  sometimes  20  per  cent,  of  the  mineral  tar 
above  described  ; is  tough  and  difficult  to  break  with  a 
hammer,  being  to  some  extent  malleable.  It  can  be  cut 
easily  with  a sharp  knife,  or  scratched  and  abraded  with  the 
finger  nail. 

Asphaltum. 

Asphaltum  is  a variety  of  bitumen  generally  found  in  a 
solid  state.  At  ordinary  temperature  it  is  brittle,  and  too 
hard  to  be  impressed  with  the  finger  nail.  It  is  black  or 
brownish  in  color,  opaque,  slightly  translucent  at  the  edge 
of  a new  fracture,  of  smooth  fracture,  and  has  little  odor 
unless  rubbed  or  heated.  It  melts  easily,  burns  with  very 
little  if  any  residue,  and  is  very  inflammable. 

It  is  found  floating  on  the  Dead  Sea,  and  in  many  places 
in  Europe.  Many  localities  in  Mexico  supply  it,  and  it 
abounds  in  the  islands  of  Barbadoes,  Trinidad,  and  Cuba, 
and  in  Ritchie  county,  West  Virginia,  and  in  New  Brunswick, 
Dominion  of  Canada.  They  all  yield,  by  distillation,  an 
inflammable  gas  ; a kind  of  bituminous  oil ; a tarry  substance 
like  coal  tar  ; and  a species  of  coke.  They  are  all  too  brittle 
when  cold,  and  too  soft  when  exposed  to  the  direct  rays  of 
a summer’s  sun,  to  be  employed  in  their  natural  state,  as 
the  cementing  substance  of  street  pavements.  A suitable 
solvent  to  render  it  fit  for  such  use,  has  been  found  in  the 
heavy  petroleum  oils,  or  the  residuum  of  refined  petroleum, 


THE  BITUMENS. 


175 


not  volatile  at  212°  Fall.,  already  mentioned.  The  result 
of  the  combination,  which  should  take  place  in  an  iron 
boiler  at  a temperature  of  about  470°  Fah.,  is  a manufac- 
tured bituminous  cement  exactly  resembling  in  composition, 
quality,  and  appearance,  the  natural  mineral  tar  obtained 
from  the  mines  of  Bastenne,  of  Gaujac,  or  from  the  sand- 
stone of  Seyssel. 

This  variety  of  bitumen,  known  as  mineral  tar,  or  bitu- 
minous or  asphaltic  cement,  whether  furnished  by  nature  in 
a nearly  pure  state,  or  formed  by  the  combination  of  other 
natural  bitumens,  under  the  general  law  that  the  more  fluid 
kinds  are  solvents  of  those  that  are  solid  or  less  fluid,  is  the 
best  and  only  suitable  cementing  substance,  or  binding 
medium,  for  asphalt  pavements  yet  discovered.  Like  all  the 
bitumens  it  owes  its  property  of  hardness  and  toughness 
under  varying  temperatures,  to  the  presence  in  suitable  pro- 
portions of  the  compounds  called  petroline  and  asphaltine, 
too  much  of  the  former  making  the  asphaltic  cement  too 
soft  in  warm  weather,  while  an  excess  of  the  latter  renders  it 
too  brittle  in  winter.  Hence  the  percentage  of  heavy  petro- 
leum oil  necessary  to  be  added  in  order  to  convert  into  a 
good  bituminous  cement,  any  particular  variety  of  asphal- 
tum,  depends  upon  the  proportion  of  petroline  and  asphal- 
tine which  the  latter  already  contains,  and  this  proportion 
varies  greatly  in  different  localities. 

No  asphaltic  cement  is  suitable  for  all  climates,  and  even 
the  natural  mineral  tar  from  Seyssel,  though  well  adapted 
for  use  upon  the  streets  of  Paris,  requires  to  be  mixed  with 
n harder  asphalt,  to  enable  it  to  withstand  exposure  to  the 
Bun  in  the  United  States. 


176 


ROADS,  STREETS,  AKD  PAVEMENTS. 


Bituminous  Limestone  (Asphalt)  Pavements. 

A capital  distinction  must  be  made  between  pavements 
of  asphalt  hereafter  described,  made  either  with  natural 
asphalt  rock,  or  with  the  refined  asphaltum  as  a cement, 
combined  with  suitable  calcareous  powder,  and  all  or  nearly 
all  of  those  attempted  imitations  of  it,  produced  by  mixing 
crude  mineral  tar,  or  manufactured  tar,  with  one  or  more 
pulverized  minerals  or  earths.  And  more  especially  must 
we  exclude  from  the  category  of  asphalt  pavements,  all  those 
patented  street  coverings  composed  of  wood -tar,  coal-tar, 
pitch,  rosin,  etc.,  mixed  with  either  sand,  gravel,  ashes, 
scoria,  sulphur,  lime,  etc.,  or  with  two  or  more  or  all  of 
them.  Some  of  them  will  produce  a tolerably  fair  sidewalk, 
but  they  are  totally  unfit  for  the  surface  of  a carriage  way. 
Some  of  the  best  of  them  will  answer  for  carriage  way  foun- 
dations. 

The  natural  asphalt  rock,  like  that  from  Seyssel  or  Val 
de  Travers,  or  other  localities  in  the  Jurassic  region,  in  order 
to  be  suitable  for  paving  carriage  ways,  should  contain  about 
11  or  12  per  cent  of  bitumen  (mineral  tar)  and  88  or  89  per 
cent  of  amorphous  carbonate  of  lime.  Inasmuch,  however, 
as  some  of  these  limestones  contain  more,  and  others  less  than 
11  or  12  per  cent  of  the  tar,  it  is  frequently  necessary  and 
always  practicable  to  obtain  a mixture  of  the  requisite 
degree  of  richness  in  bitumen,  by  combining  those  of  differ- 
ent qualities  together,  or,  if  none  but  a rock  poor  in  bitumen 
is  procurable,  the  same  result  may  be  obtained  by  adding 
mineral  tar  to  it. 

The  rock  should  be  of  the  fine-grained  variety,  of  toler- 
ably close  texture,  and  composed  of  pure  carbonate  of  lime 


ASPHALT  PAVEMENT. 


17? 


so  uniformly  and  homogeneously  impregnated  with  the  bitu- 
men, that  a cut  made  with  a sharp  knife  will  show  neither 
pure  white  nor  jet  black  spots,  but  be  of  a brownish  liver 
color,  mottled  with  grey. 

When  asphalt  rock  of  this  character  is  heated  to  a 
temperature  of  200°  to  212°  Fah.,  the  bitumen  becomes 
soft,  the  grains  of  limestone  separate  from  each  other,  and 
the  mass  crumbles  into  a partially  coherent  powder.  If 
this  powder,  while  still  hot,  be  powerfully  compressed  by 
ramming,  tamping,  or  rolling,  the  molecules  will  again 
unite,  and  the  mass  when  cold  will  assume  all  the  essential 
qualities  of  the  original  rock,  but  in  a superior  degree,  as 
regards  toughness,  hardness  and  incompressibility.  This 
is  the  whole  theory  of  asphalt  road  coverings,  as  applied  to 
the  street  pavements  in  Paris  and  elsewhere. 

Foundations  for  Asphalt  Pavements. 

The  pavement  foundation  should  be  preferably,  cement, 
concrete,  or  rubble  stones  filled  in  with  concrete  made  after 
the  same  formula,  and  laid  in  the  same  manner  and  to  the 
same  thickness,  heretofore  described  for  a pavement  of  stone 
blocks  ; or  it  may  be  six  to  eight  inches  of  suitably  com- 
pacted broken  stone  ; or  an  old  broken  stone  road  carefully 
cleaned  by  scraping  and  sweeping,  and  then  covered  to  an 
even  surface  with  a coat  of  mortar ; or  an  old  cobble,  or 
stone  block  pavement,  with  the  joints  raked  out  to  a depth  of 
about  one  inch,  and  then  cleaned  off  and  coated  with  mor- 
tar. Even  a badly  worn  pavement  of  coal-tar  concrete,  or 
other  kindred  mixtures,  may  be  the  foundation,  under  suit- 
able precautions.  The  mortar  used  for  surfacing  the  foun- 
dation may  be  composed  of  one  volume  of  common  lime 
8* 


178 


ROADS,  STREETS,  AND  PAVEMENTS. 


paste,  one  volume  of  the  paste  of  Rosendale  or  other  equiva- 
lent cement,  and  seven  to  eight  volumes  of  coarse  sharp 
sand.  If  standard  Portland  cement  be  used,  the  volume  ol 
lime  paste  may  be  doubled,  and  the  volume  of  sand  increased 
one-half,  producing  a mortar  containing  cement  paste  cue, 
lime  paste  two,  and  sand  ten  to  twelve. 

If  a new  foundation  has  to  be  prepared,  it  should  be  of 
good  cement  concrete,  and  for  streets  subjected  to  heavy 
traffic  not  less  than  6 inches  thick  if  upon  firm  and  compact 
soils,  and  rarely  more  than  9 or  10  inches  if  the  road  bed 
be  wet,  spongy,  or  clayey.  It  should  be  compacted  to  an 
even  surface  parallel  to  that  of  the  new  pavement,  so  that 
the  latter  can  be  applied  in  a sheet  of  uniform  thickness. 

Heating  the  Asphalt. 

The  asphalt  rock,  previously  pulverized  by  grinding,  is 
brought  to  a uniform  temperature  of  250°  to  260°  Fah.,  in 
iron  heaters,  and  in  this  condition  is  conveyed  in  wlieel-bar- 
rows  with  sheet  iron  bodies  to  the  place  where  it  is  to  be 
used.  If  the  heaters  be  arranged  upon  wheels  so  as  to  be 
portable,  they  can  be  kept  in  close  proximity  to  the  point  of 
application,  in  which  case  the  hot  material  may  be  taken  out 
with  long  handled  shovels,  and  deposited  directly  upon  the 
foundation  in  its  proper  place,  but  it  will  generally  be  found 
convenient  to  convey  it  in  wheel-barrows. 

The  material  is  not  in  fit  condition  for  use  until  all  the 
moisture  has  been  driven  from  it,  and  it  should  not  be 
applied  upon  a cement-concrete  foundation  until  the  latter 
has  had  some  days  to  set,  nor  in  any  case  upon  any  kind  of 
foundation  until  its  surface  has  become  perfectly  dry.  If 
laid  upon  a damp  surface  the  heat  vaporizes  the  ir  oisture. 


ASPHALT  PAVEMENT. 


179 


and  the  steam,  escaping  through  the  powder,  prevents  a 
thorough  and  complete  cohesion  of  the  particles,  and  ren- 
ders the  pavement  imperfect.  When  it  is  impossible  or  incon- 
venient to  wait  for  the  surface  of  the  foundation  to  become 
dry,  a first  coating  of  asphalt,  one-fourth  of  an  inch  thick, 
may  be  applied,  to  be  followed  when  hard  by  the  final  cov- 
ering. By  this  precaution  the  injurious  etfects  of  the  steam 
created  by  the  hot  powder,  will  be  avoided.  For  this  lower 
coat  the  asphalt  may  be  of  poorer  quality. 

Applying  the  Asphalt. 

The  hot  powder  having  been  carefully  spread  upon  the 
foundation  with  an  iron  rake,  to  a depth  exceeding  by  two- 
fifths  the  ultimate  thickness  required,  is  then  compacted  by 


Fig.  57. 

ramming  with  iron  pestles,  kept  sufficiently  hot  in  portable 
furnaces  to  prevent  a too  rapid  cooling  of  the  asphalt.  The 
rrmming^sheuld  first  be  done  cautiously  with  light  blows, 


gradually  increasing  in  energy,  special  care  being  taken  at 
Ll.e  junction  of  the  hot  powder  with  that  previously  laid. 
The  finished  pavement  should  be  smooth  and  even,  with 
from  If  to  2 inches  thickness  of  asphalt,  except  upon  streets 


180 


ROADS,  STREETS,  AND  PAVEMENTS. 


where  the  traffic  is  very  heavy,  when  the  thickness  may 
advantageously  be  from  to  3 inches.  The  iron  rammer, 
Fig.  57,  may  be  circular,  square,  or  rectangular  on  the  face, 
and  should  weigh  from  14  to  16  pounds.  After  the  rammers, 
hot  smoothing  irons,  Fig.  58,  are  passed  over  the  surface,  in 
order  to  give  it  a High  degree  of  finish. 

It  is  usual  to  lay  this  pavement  in  transverse  strips  from 
curb  to  curb,  or  from  gutter  to  gutter,  of  a uniform  width  of 
4 to  6 feet,  care  being  taken  to  cut  the  outer  edge  of  each 
strip  to  a rebate  while  it  is  yet  soft  as  shown  in  Fig.  59,  so 


Fig.  59. 


that  the  hot  asphalt  of  the  succeeding  strip  may  lap  over  and 
firmly  unite  with  it.  If  the  strip  has  become  cold,  from 
interruption  of  the  work  or  other  cause,  some  of  the  hoi 
asphaltic  cement  should  be  applied  go  the  rebate  with  a 
brush,  in  order  to  insure  a close  and  powerful  cohesion  in 
the  joint.  In  two  or  three  hours  after  the  work  is  done  the 
road  is  sufficiently  hard  to  be  thrown  open  to  traffic.  It  is 
usual  to  first  spread  over  it  a light  layer  of  loamy  sand. 

The  consolidation  is  sometimes  effected  with  heavy  iron 
rollers  of  different  weights,  beginning  with  the  lightest  and 
finishing  off  with  the  heaviest,  but  a roller  containing  only 
a single  cylinder,  if  sufficiently  heavy  to  be  effective,  is  apt 
to  cause  the  soft  asphalt  to  rise  up  in  front  of  it,  and  even 
to  tear  it  asunder  as  the  temperature  becomes  lower.  Two 
or  three  rollers,  placed  close  together  in  the  same  frame,  one 
behind  the  other,  would  be  less  objectionable. 


ASPHALT  PAVEMENT. 


181 


The  method  of  consolidation  with  rammers  is  believed  to 
be  the  best,  all  things  considered. 

It  is  important  that  the  surface  should  be  evenly  finished 
to  the  required  grade,  and  be  free  from  elevations  and  depres- 
sions. If  otherwise  the  wear  will  be  more  severe,  in  conse- 
quence of  the  shocks  and  blows  created  whenever  a wheel 
rises  and  falls  upon  the  uneven  surface.  Moreover,  rainwater 
and  all  noxious  fluids  should  drain  off  freely,  which  they 
could  not  do  from  a rough  pavement,  and  as  the  asphalt  is 
impervious  to  water,  they  would  stand  in  pools  until  cleaned 
off  or  removed  by  evaporations. 

There  can,  of  course,  be  no  vertical  absorption  from  rains, 
through  such  a covering.  There  will  also  be  no  lateral  ab- 
sorption if  suitable  drainage  has  been  provided.  The  road 
bed  will  therefore  remain  dry  at  all  seasons  of  the  year,  and 
no  upheavals  from  frost  need  ever  be  apprehended. 

Asphalt  Pavements  without  Bituminous 
Limestone. 

When  it  is  desired  to  construct  an  asphalt  pavement, 
without  using  the  bituminous  limestone  from  the  Jurassic 
region  which,  as  already  described,  contains  both  the  matrix 
or  binding  material,  and  the  body  cemented  together,  and 
which  after  disintegration  by  heat,  or  by  grinding,  is  capable 
of  being  re-united  under  a new  form,  and  especially  in 
the  form  of  a monolithic  sheet  suitable  for  street  coverings, 
there  are  three  essential  points  demanding  consideration, 
viz  : 

First * To  obtain  a suitable  bituminous  or  asphaltic 
cement. 

Second . To  obtain  a solid  material  in  the  form  of 


182 


ROADS,  STREETS,  AND  PAVEMENTS. 


powder,  fit  to  replace  the  amorphous  carbonate  of  lime  of  the 
natural  asphalt  rock. 

Third . To  combine  these  two  in  such  manner  that  they 
will  answer  the  purpose  of  a pavement.  These  points  will 
be  briefly  considered  in  their  regular  order. 

The  Asphaltic  Cement. 

First . The  imported  mineral  tar,  after  proper  treat- 
ment to  adapt  it  to  our  climate,  by  adding  a small  quantity 
of  refined  asphaltum,  is  a good  asphaltic  cement.  When, 
however,  it  is  desired  to  manufacture  a suitable  cement  from 
the  crude  materials,  the  variety  of  bitumen  known  as  asphal- 
tum  or  asphalt  is  employed  as  the  basis. 

The  asphalts  from  different  localities  differ  very  much  in 
the  proportion  of  asphaltine  and  petroline  which  they  con- 
tain. Too  much  asphaltine  renders  the  cement  brittle  in 
cold  weather,  while  it  will  become  too  soft  in  summer  if  it 
contains  an  undue  quantity  of  petroline.  No  natural  asphalt, 
whether  liquid  or  solid,  has  yet  been  found  suitable  for  all 
climates  and  seasons,  and  it  is  necessary  to  mix  two  or  more 
together,  in  order  to  arrive  at  satisfactory  results,  having 
first  ascertained  the  standard  quality  of  each. 

The  asphalts  in  common  use  in  this  country  are  derived 
from  deposits  found  in  the  islands  of  Cuba  and  Trinidad ; 
from  Ritchie  county,  West  Virginia,  and  from  the  province 
of  New  Brunswick.  The  two  last  named,  known  respectively 
as  Grahamite  and  Albertite,  are  pure  asphalts,  containing 
little  if  any  foreign  impurities,  while  the  others  contain 
from  20  to  30  per  cent  of  deleterious  refuse  matter,  which 
has  to  be  separated  by  a careful  process  of  refining.  They 
all  differ  in  the  amount  of  asphaltine  which  they  contain, 


ASPHALT  PAVEMENT. 


183 


fchere  being  the  most  in  Grahamite  and  Albertite,  less  in  the 
Cuban,  and  least  in  that  from  Trinidad.  There  is  a liquid 
asphalt  or  mineral  tar,  brought  from  the  isthmus  of  Tehuan- 
tepec, which  contains  less  asphalt  than  the  Trinidad.  It 
contains  about  2 per  cent  of  sulphur  and  a large  proportion 
of  water,  as  received  in  the  market,  from  which  it  has  to  be 
separated  by  refining. 

These  natural  asphalts,  having  each  been  brought  by 
refining  to  a standard  point  of  specific  gravity  and  purity, 
may  be  used  separately,  or  two  or  more  of  them  may  be 
mixed  together,  as  the  basis  of  the  asphaltic  cement.  It  will 
be  necessary  in  using  only  the  solid  asphaltums  to  add,  at  a 
suitable  temperature — say  from  250°  to  300°  Fahrenheit — 
a small  per  centage  of  the  proper  solvent,  such  as  the  heavy 
oils  or  “ still  bottoms,”  produced  in  the  process  of  refining 
crude  petroleum,  in  order  to  render  the  cement  fit  for  pave- 
ments, and  enable  it  to  withstand  the  changes  of  temperature 
in  the  locality  where  it  is  to  be  used.  The  precise  quantity 
of  heavy  oil  that  it  would  be  necessary  to  add  to  any  one 
asphalt,  would  not  be  likely  to  suit  another,  or  the  mixture 
of  two  or  more  of  them.  Chemical  research  and  experiment 
can  alone  determine  this  point.  A liquid  bitumen  con- 
taining asphaltine  and  petroline  in  the  requisite  propor- 
tions to  produce  the  desired  result  may  replace  the  still 
bottoms. 

A serious  impediment  to  the  successful  use  of  asphalt 
for  pavements  in  this  country,  is  the  condition  in  which 
they  are  shipped  from  the  island  of  Trinidad  and  other 
localities  where  the  deposits  are  found. 

The  operation  of  refining — improperly  so  called — at  the 
mines,  is  very  imperfectly  done,  so  that  variable  and  some* 


184 


ROADS,  STREETS,  AND  PAVEMENTS. 


times  large  percentages  of  refuse  and  deleterious  matter, 
such  as  earth,  vitrified  sand,  cinders,  ashes,  etc.,  are  con- 
tained in  the  material  as  supplied  for  use.  Dr.  Ure,  in 
several  analyses,  states  that  he  found  from  20  to  30  per  cent 
of  these  impurities.  This  variable  quality  of  the  asphalt, 
not  only  seriously  impairs  its  value,  but  likewise  renders  the 
results  of  its  use  uncertain,  when  fixed  rules  as  to  propor- 
tions, which  have  been  established  for  an  article  of  standard 
value,  are  adhered  to. 

The  manner  in  which  the  crude  material  is  treated  for 
the  purpose  of  separating  these  foreign  substances,  and  dis- 
tilling volatile  matter,  is  faulty.  The  heat  is  often  applied 
in  an  irregular  and  unsystematic  manner,  and  with  such 
carelessness  as  frequently  to  destroy  by  overheating  much  of 
the  most  valuable  part  of  the  asphalt,  leaving  the  material 
in  such  condition,  that  when  employed  for  pavements,  even 
after  the  best  formula  honestly  and  closely  followed,  no 
good  results  can  be  obtained. 

The  preparation  of  asphaltic  cement,  suitable  for  car- 
riage way  pavements,  requires  improved  machinery,  scien- 
tific supervision,  and  systematic  labor,  all  of  which  will 
necessarily  enhance  the  first  cost  of  the  article.  None  of 
them  can,  however,  be  safely  omitted. 

Any  process  which  will  not,  with  reasonable  certainty, 
secure  the  uniform  application  of  heat  to,  and  proper  super- 
vision over,  the  distillation  and  refining  necessary  to  bring 
the  material  to  its  proper  condition,  will  be  likely  to  end  in 
more  or  less  complete  failure,  for  one  or  the  other  of  the  fol- 
lowing reasons,  namely,  (1)  it  will  either  result  in  the 
destruction  of  some  of  the  valuable  properties  of  the  bitumen, 
or,  (2)  it  will  impair  its  fitness  for  pavements  by  the  imper- 


THE  POWDER. 


185 


feet  evolution  and  distillation  of  volatile  or  other  injurious 
or  useless  matter,  such  as  water  and  light  volatile  oils. 

The  asphaltic  cement  when  properly  prepared  must  be 
soft  even  in  cold  weather,  must  give  by  distillation  a hy- 
dro-carbon oil  of  a fire  test  not  less  than  200°  Fah.,  must 
contain  no  water  or  any  ingredient  soluble  in  water  01 
the  urine  of  animals,  and  must  contain  nothing  that  is 
oxidizable,  or  that  can  be  affected  by  the  elements  to 
any  serious  degree.  Changes  of  temperature  will  not 
render  it  very  brittle  in  winter  and  soft  in  summer,  even 
in  the  variable  climate  of  the  United  States,  although  the 
formula  that  would  suit  Boston  or  New  York,  would  not 
answer  in  either  New  Orleans  or  Key  West,  more  asphaltine 
being  necessary  in  the  cement  intended  for  the  warmer 
climates. 

In  striking  contrast  to  the  material  above  described,  in 
every  conceivable  respect,  are  all  those  mixtures  of  wood-tar, 
coal-tar,  pitch,  rosin,  etc.,  which  have  brought  such  unjust 
disrepute  upon  asphalt  pavements. 

The  Powder. 

Second . The  specious  and  altogether  worthless  street 
coverings,  erroneously  called  asphalt  pavements,  to  which 
brief  reference  has  already  been  made,  have  owed  their  uni- 
form failure,  not  so  much  to  the  sand,  gravel,  lime,  etc., 
employed  to  give  them  strength  and  body,  as  to  the  entire 
absence  of  a suitable  cementing  medium. 

A fair  pavement  can  be  made  by  properly  mixing  any 
kind  of  fine  sand  with  the  asphaltic  cement  above  described, 
but  nothing — not  even  the  pure  amorphous  carbonate  of 
lime  contained  in  the  natural  asphalt  rock — would  make  a 


186 


ROADS,  STREETS,  AND  PAVEMENTS. 


pavement  of  any  value,  if  coal  or  wood- tar,  pitch  or  rosin, 
or  any  combination  of  them,  furnishes  the  matrix. 

The  best  material  yet  found  in  the  natural  state,  for  the 
body  of  the  mixture,  is  very  fine  sand,  carefully  screened 
from  all  coarse  particles  and  gravel,  and  composed  partly  of 
calcareous  matter  in  which  the  calcareous  ingredient  exists 
mostly  in  the  form  of  powder.  This  sand,  when  rubbed 
between  the  fingers,  does  not  convey  the  idea  of  being  sharp 
and  gritty,  but  feels  something  like  fine  Indian  meal.  It 
should  contain  25  to  30  per  cent  of  calcareous  matter,  and 
preferably  40  or  even  50  per  cent. 

When  such  a material  cannot  be  found,  it  can  be  produced 
by  mixing  fine  silicious  sand  and  pulverized  marl,  and  where 
marl  is  abundant  it  can  be  used  alone,  being  first  ground  to 
a fine  powder.  The  sand  should  be  as  absorbent  in  char- 
acter as  can  be  found,  and  the  ratio  of  absorption  among 
different  kinds  will,  as  a general  rule,  vary  directly  with  the 
quantity  of  porous  calcareous  particles  which  it  contains. 

Mixing  the  Cement  and  Powder. 

Third . The  sand  and  the  asphaltic  cement  are  mixed  to- 
gether at  a temperature  of  250°  to  300°  Fahrenheit — not 
higher — in  the  proportion  by  weight  of  80  parts  of  sand 
to  20  parts  of  cement.  The  two  ingredients  are  heated 
separately. 

In  conducting  operations  on  a small  scale,  the  cement 
may  be  heated  in  an  ordinary  furnace  kettle,  and  the  sand 
in  a broad  shallow  sheet-iron  vessel,  so  arranged  that  a fire 
can  be  maintained  under  it.  The  hot  sand  is  added  to  the 
cement  in  small  quantities,  accompanied  by  frequent  stir- 
ring, and  when  a homogeneous  mixture  has  been  obtained 


TIIE  SAKD  HEATER. 


187 


in  the  required  proportions,  it  is  ready  to  be  applied  upon 
the  street,  in  the  manner  al- 
ready described  for  pavements 
of  compressed  asphalt  rock. 

Calcareous  sand  suffers  injury 
if  heated  much  above  300° 

Fahrenheit,  so  that  a watchful 
care  is  necessary  in  this  part  of 
the  process. 

For  extensive  work  better 
appliances  for  heating  and  mix- 
ing the  materials  than  those 
above  indicated  would  be  econ- 
omical. For  the  sand,  a hollow 
iron  cylinder  about  2 feet  in  di- 
ameter and  10  to  12  feet  long, 
set  horizontally  in  a furnace 
and  revolving  slowly,  or  two 
such  cylinders  placed  side  by 
side,  has  been  found  to  answer 
very  well. 

Such  a sand  heater  is  shown 
in  Figs.  60  and  61.  Fig.  60  is  a 
section  on  AB  of  Fig.  61,  and 
Fig.  61  is  a side  view  and  sec- 
tion on  CD  of  Fig.  60.  E is  the 
inlet  for  sand  ; F outlet  for 
screened  sand ; G outlet  for 
screenings  ; H fireplace  ; I the 
chimney  temporarily  lowered  ; 
and  K the  driving  pulley.  The  sand  is  conveyed  from  the 


188 


ROADS,  STREETS,  AXD  PAVEMENTS. 


inlet  li  into  the  revolving  heater  by  an  archimedian  screw. 

At  V is  a valve,  lightly 
counterpoised  so  as  to  open 
and  allow  any  sand  to 
escape  which  may  get  into 
the  furnace  flue  S,  which 
surrounds  the  heater. 
The  whole  machine  is 
mounted  on  a pair  of 
wheels  so  as  to  be  portable. 

The  jsphalt  mixer  in 
which  tne  melted  cement  is 
incorporated  with  the  hot 
sand,  consists  of  a hori- 
zontal twin  pug-mill  6 to 
8 feet  in  length.  The  two 
horizontal  shafts  are  par- 
allel to  each  other,  and 
about  1 foot  9 inches  apart, 
each  provided  with  arms 
14  or  15  inches  long,  set 
at  right  angles  to  the 
shaft.  The  arms  from  the 
two  shafts  therefore  over- 
lap each  other  about  7 
inches.  The  bottom  of 
the  pugmill  is  composed 
of  parts  of  two  cylinders 
of  boiler  iron,  respectively 
tangent  to  the  ends  of  the 
two  sets  of  shaft  arms. 


7* 


THE  ASPHALT  MIXER. 


189 


Directly  over  this  pugmill  is  a top  mixer,  in  which  the 
melted  cement  and  hot  sand  are  first  mixed  together,  and 
into  which  they  are  measured  in  the  proper  proportions,  with 
vessels  suspended  above  on  movable  pulleys.  See  Figs.  62 
and  63.  Fig.  62  is  an  end  view  ; Fig.  63  a side  view  and 
section  on  p r of  Fig.  62  ; a top  mixer  ; b twin  mixer  ; c 
asphalt  measure  ; d sand  measure  and  hoisting  apparatus  ; 
e driving  chain  for  top  mixer  ; / wooden  platform  for  work- 
men ; g fire  room  ; h fixtures  for  operating  sliding  doors  in 
bottom  of  top  mixer  for  supplying  the  twin  mixer ; i driv- 
ing wheel  ; Tc  pinion,  and  l driving  cogwheel.  When  in 
operation  the  shafts  of  the  twin  mill  revolve  slowly  in  oppo- 
site directions,  the  ends  of  both  sets  of  arms  ascending 
between  the  two  axes,  so  that  their  action  is  to  lift  the  mate- 
rial constantly  and  let  it  fall,  thus  securing  a thorough  and 
homogeneous  mixture.  The  whole  apparatus  is  arranged 
with  a furnace  underneath. 

It  is  convenient  to  have  both  the  sand  heater  and  mixer 
on  wheels,  so  that  they  can  be  readily  moved  from  place  to 
place  as  circumstances  require. 

Applying  the  Mixture. 

The  asphalt,  having  been  prepared  in  the  manner  thus 
indicated,  is  in  the  condition  while  hot  of  partly  coherent 
powder,  in  all  respects  resembling  the  powdered  bituminous 
limestone,  and  in  its  use,  the  directions  given  for  lay- 
ing pavements  with  that  material  should  be  closely  fol- 
lowed. 

When  the  foundation  is  of  broken  stone,  newly  laid  for 
the  purpose,  great  care  should  be  taken  to  guard  against 
subsequent  settlement.  The  stone,  or  a mixture  of  stone 


190 


HOADS,  STREETS,  AND  PAVEMENTS. 


and  gravel,  should  be  of  all  sizes  from  2^  inches  in  longest 
dimensions  down  to  fragments  not  larger  than  peas,  in  order 
to  reduce  the  voids  to  a minimum.  By  mixing  it  with  one- 
fourth  to  one- third  of  its  volume  of  some  of  the  best  coal 
tar  mixtures  used  for  patent  sidewalks,  heating  the  mixture, 
and  then  compacting  it  by  rolling  or  ramming  in  two  layers 
of  3 to  4 inches  each,  a good  foundation,  although  inferior 
to  one  of  hydraulic  concrete,  will  be  obtained.  When  neces- 
sary to  save  expense,  the  use  of  the  coal  tar  compound  may 
be  restricted  to  the  top  layer,  or  even  to  a surface  coating 
of  the  top  layer,  which  should  be  forced  well  into  the  inter- 
stices during  the  process  of  ramming  or  rolling.  But  all 
these  devices  for  cheapening  a foundation  are  certain  to 
impair  its  strength  and  solidity. 

One  of  the  patent  asphalt  roadway  pavements  is  described 
to  consist  (1)  of  a foundation,  5 to  6 inches  thick,  of  broken 
stone  heated  and  mixed  with  a bituminous  compound,  topped 
otf  (2)  with  a thin  binding  layer  of  small  gravel  and  stone, 
over  which  is  placed  (3)  a thin  coating  of  liquid  asphalt. 
Then  follows  (4)  a layer  i to  ^ inch  thick  of  asphaltic  mas- 
tic ; then  (5)  another  coating  of  liquid  asphalt ; and  finally 
(6)  a top  layer  1^  to  inches  thick  of  asphaltic  mastic.  It 
is  needless  to  say  that  if  the  nomenclature  here  employed  be 
correct,  and  coal  tar  or  some  patented  compounds  are  not 
referred  to,  this  will  be  a good  pavement  for  footpaths, 
although  unnecessarily  thick,  but  will  not  be  hard  enough 
for  carriage  ways.  By  replacing  the  four  top  layers — the 
third,  fourth,  fifth,  and  sixth — by  genuine  asphalt  as  above 
recommended  for  carriage  ways,  a good  street  pavement 
would  be  obtained. 


ASPHALT  BLOCK  PAVEMEHT. 


191 


Asphalt  Block  Pavement. 

Mention  was  made  on  page  177,  of  the  superior  tough- 
ness, hardness,  and  incompressibility,  conferred  on  bitumin- 
ous limestone  by  compressing  it  while  hot.  This  property 
characterizes  any  genuine  asphalt  mixture  suitable  for  pav- 
ing purposes,  and  advantage  has  been  taken  of  it,  in  first 
forming  the  material  into  rectangular  blocks  under  a heavy 
pressure,  and  then  laying  them  in  courses  across  the  street, 
substantially  after  the  manner  followed  in  constructing  the 
best  stone  block  pavement.  It  is,  perhaps,  needless  to  say 
that  a pavement  of  this  kind,  composed  of  good  materials, 
properly  prepared,  and  laid  upon  a firm  and  unyielding 
foundation,  should  be  a good  one.  Specimens  of  it  have 
been  on  trial  for  some  years  in  San  Francisco,  Oak,  where  it 
is  styled  by  the  patentee  the  Imperishable  Stone-Block  Pave- 
ment. The  blocks  are  made  with  Trinidad  asphaltum, 
softened  with  7 to  9 per  cent  of  the  heavy  oils  or  still  bot- 
toms, used  in  preparing  the  asphaltic  cement  described  on 
pages  182  to  185.  This  preparation  is  mixed  with  hot 
powdered  limestone,  or  powdered  furnace  slag,  and  then  com- 
pressed 'v  ih  a force  of  about  50  tons  into  blocks  measuring 
4 inches  5 inches  by  12  inches.  • The  pressure,  which  is 
applied  S the  narrowest  face  of  the  block,  exceeds  one  ton 
to  the  square  inch.  The  limestone  or  slag  is  not  required 
to  be  of  the  firmness  of  impalpable  powder,  but  is  composed 
of  grains  of  all  sizes  from  dust  up  to  the  size  of  a small  pea. 

The  blocks  are  laid  close  together  on  their  longest  edges, 
in  courses  across  the  street,  breaking  joints  lengthwise  of  the 
street,  the  joints  being  filled  with  suitable  asphaltic  cement 
so  as  to  render  the  pavement  water  tight.  The  foundation 


192 


ROADS,  STREETS,  AND  PAVEMENTS. 


should  be  firm  and  stable,  such  as  the  best  of  those  described 
on  pages  143  to  149.  This  pavement  while  new  would  be 
nearly  as  smooth  as  that  of  the  continuous  sheet  of  asphalt 
heretofore  described,  but  the  wear  of  heavy  traffic  would,  in 
a short  time,  crumble  off  the  edges  of  the  blocks  and  open 
the  joints  at  the  surface  sufficiently  to  give  the  horses  a foot- 
hold, without  impairing  the  imperviousness  of  the  covering. 
It  is  suggested  that  it  would  be  better  to  form  the  blocks 
with  slightly  truncated  or  rounded  edges,  so  as  to  give  the 
requisite  foothold  when  the  pavement  is  laid,  rather  than  to 
secure  the  same  end  by  the  irregular  and  ragged  abrasion 
caused  by  use.  As  they  are  homogeneous  in  toughness  and 
hardness,  the  blocks  can  be  taken  up,  when  their  surfaces  be- 
come uneven  from  unequal  wear,  and  relaid  in  mortar,  bottom 
sides  up,  with  all  the  smoothness  of  a new  pavement.  It  may 
be  added  that  the  process  of  refining  and  careful  manipula- 
tion described  on  pages  182  to  185,  is  equally  necessary 
whether  the  material  be  applied  as  a monolithic  sheet,  or 
as  blocks,  and  any  mixture  that  is  suitable  for  the  former  is 
also  suitable  for  the  latter  ; also,  that  a form  of  sand  is  not  a 
proper  foundation  in  either  case. 

Merits  of  Asphalt  Pavement. 

The  advantages  possessed  by  monolithic  asphalt  pave- 
ments constructed  by  either  of  the  two  methods  above 
described  are  (1)  that  they  produce  no  dust  and  therefore  no 
mud  ; (2)  are  comparatively  noiseless,  the  clicking  of  the 
horses’  feet  excepted  ; (3)  do  not  absorb  and  retain  noxious 
liquids  but  facilitate  their  prompt  discharge  into  the  side 
gutters  and  sewers ; (4)  they  are  impermeable  and  emit  no 
noxious  vapors  themselves,  or  allow  their  emission  from  the 


MERITS  OF  ASPHALT  PAVEMEHT. 


193 


subsoil ; (5)  they  reduce  the  force  of  traction  and  conse- 
quently the  expense  of  wear  and  tear  upon  animals  and 
vehicles  to  a minimum  ; and  (6)  although  they  do  not  furnish 
as  secure  a foothold  for  animals  drawing  heavy  loads  as 
stone  blocks  in  narrow  courses,  or  as  cobble  stones,  still  they 
do  not  become  polished  and  slippery  from  continued  wear. 

They  are  adapted  to  all  streets  with  a grade  not  steeper 
than  1 in  48  to  1 in  50,  except  perhaps  those  thickly  crowded 
with  heavy  loads,  and  liable  to  be  kept  constantly  wet  and 
slippery  during  the  busiest  hours  of  the  day,  from  the 
accumulated  urine  of  animals,  and  where  the  vehicles  are 
subject  to  the  inconvenience  of  frequent  and  sudden  halts, 
starts,  and  sharp  turns,  like  many  of  the  streets  in  the  lower 
portions  of  the  city  of  New  York,  and  especially  like  Broad- 
way below  Fourteenth  street,  over  every  transverse  section 
of  which,  from  12,000  to  14,000  vehicles  of  all  kinds  pass 
daily.  In  such  localities  it  seems  necessary  that  the  pave- 
ment should  possess  that  roughness  of  surface  conferred  by 
blocks  laid  with  open  joints  directly  or  diagonally  across 
the  street. 

Where  the  traffic  is  of  a lighter  character,  or  where  there 
is  ample  room  for  conducting  it  without  inconvenience,  or 
where  a large  proportion  of  it  is  pleasure  driving,  and  par- 
ticularly where  the  streets  are  lined  with  residences  on  either 
side,  the  many  advantages  of  a good  asphalt  pavement,  its 
cleanliness,  its  noiselessness,  and  its  imperviousness  to  noxious 
fluids — important  features  in  which  it  stands  unrivaled — 
should  not  be  lost  sight  of. 

Another  consideration  demanding  the  exercise  of  sound 
judgment  is  that  no  pavement  combines  the  opposite  require- 
ments of  an  even  surface  fox  the  wheels,  and  a suitably 

9 


194 


ROADS,  STREETS,  AND  PAVEMENTS. 


rough  one  for  the  horses  to  travel  upon,  and  a compromise 
of  advantages  must  therefore  be  made  in  most  cases. 

The  wear  of  asphalt  is  quite  small,  its  diminished  thick- 
ness under  traffic  being  principally  due  to  compression  and 
not  to  abrasion. 

It  has  been  ascertained  in  London  that  some  specimens  of 
Val  de  Travers  asphalt,  subject  to  four  years’  wear  in  a street 
of  the  greatest  traffic,  had  diminished  about  one-ninth  in 
thickness,  while  its  specific  gravity  had  increased  in  about 
the  same  ratio. 

Some  of  the  same  material  after  fifteen  years’  wear,  in 
Rue  de  Bergere,  Paris,  was  found  to  have  lost  12 \ per  cent 
of  its  thickness,  but  only  5 per  cent  of  its  total  weight. 

This  material  is,  to  a great  degree,  a non-conductor  of 
vibration  and  of  sound.  It  is  much  less  sonorous  than 
granite,  and  gives  out  very  little  noise  from  wheels.  When 
properly  laid,  loaded  vehicles  make  no  impression  upon  it. 
A four-wheeled  truck  weighing  three  tons,  carrying  a boiler 
weighing  twenty-one  tons,  passed  over  a piece  of  asphalt 
pavement  in  Fifth  Avenue  near  Twenty-fourth  street,  New 
York,  without  leaving  any  mark.  This  occurred  in  the  last 
week  in  June. 

The  asphalt  covering  rarely  exceeds  two  or  three  inches 
in  thickness,  and  readily  adapts  itself  to  any  subsidence  or 
movement  of  the  surface  on  which  it  rests.  A firm  and  un- 
yielding foundation  is  therefore  an  indispensable  requisite  of 
a good  asphalt  pavement.  Concrete  is  recommended  for 
this  purpose,  in  all  localities. 

As  the  asphalt  surface  is  smooth  and  even  when  properly 
laid,  offering  but  a trilling  obstacle  to  surface  drainage,  a 
comparatively  flat  cross  section  is  admissible,  and,  as  a 


COST  OF  ASPHALT  PAVEMENT. 


195 


precaution  against  horses  falling,  may  be  regarded  as  indis- 
pensable. The  inclination  toward  the  side  gutters  should 
not  exceed  1 in  60.  For  the  same  reason  the  grades  must  be 
kept  low,  preferably  not  steeper  than  1 in  50,  in  order  that 
great  extra  effort  may  be  avoided  either  in  pulling  on  the 
up  grades,  or  in  holding  back  on  those  that  are  descending. 

Streets  with  an  undulating  grade  should  not  be  paved 
with  asphalt  upon  those  portions  steeper  than  1 in  50. 

With  suitable  appliances,  labor  at  $2.00  per  day,  natural 
American  hydraulic  cement  at  $1.50,  or  Portland  cement  at; 
$4.00  per  barrel,  and  refined  asphaltic  cement  at  1^  cents 
per  pound,  an  asphalt  pavement  of  the  kind  described  on 
page  183,  and  following,  can  be  laid  for  $2.70  to  2.80  per 
square  yard,  exclusive  of  profit  to  the  contractor,  as  follows  : 

Concrete  foundation  6 inches  thick  (labor  and  material),  $1.40  to  $1.45 


Asphalt  covering  2 inches  thick  do  do 1.30  to  1.35 

Total $2.70  $2.80 


This  includes  nothing  for  earth  work,  but  supposes  the 
road  bed  to  have  been  suitably  excavated  or  filled  in,  as  the 
case  might  be,  in  readiness  for  the  minor  adjustments  of 
grade  and  cross  section,  preparatory  to  laying  the  foundation. 

If  the  natural  asphalt  rock  from  Seyssel  or  Yal  de  Travers 
be  used  for  the  covering,  80  to  90  cents  per  square  yard 
will  have  to  be  added  to  the  foregoing  prices.  In  the  city 
of  Washington,  these  pavements  of  the  natural  rock  have 
cost,  within  the  last  six  years,  $4.25  per  square  yard  inclu- 
sive of  profit,  although  the  payment  was  made  in  depre- 
ciated securities. 

Among  intelligent  people,  there  are  many,  more  or  less 
familiar  with  bitumen  and  its  uses,,  who  claim  that  nc 


196 


ROADS,  STREETS,  AND  PAVEMENTS. 


asphalt  pavement  can  be  produced,  equal  to  that  made  with 
natural  asphalt  rock,  because  that  rock  is  natural.  This 
assumes  that  nature  leaves  her  work  so  nearly  perfect,  that 
improvement  upon  it  is  impossible,  a premise  that  cannot  be 
maintained.  The  crude  petroleums  possess  very  little  value 
until  they  have  passed  through  the  laboratory  of  the  prac- 
tical chemist ; and  the  mineral  tars  of  the  Jurassic  region, 
when  used  for  enriching  the  meagre  bituminous  limestone, 
or  when  added  to  that  material  in  the  manufacture  of  bitu- 
minous mastic,  are  always  refined  beforehand.  The  asphal- 
tic cement  to  which  reference  has  been  made  on  pages  182  to 
185  is  prepared  from  the  natural  bitumens,  and  is  identical 
in  chemical  composition,  in  color,  tenacity,  and  all  other 
physical  features,  with  the  best  refined  mineral  tar,  with  this 
advantage  over  the  mineral  tar  contained  in  the  asphalt 
rock,  that  its  consistency  may  be  adapted  to  any  climate, 
while  the  other  is  suited  to  but  one.  What  is  wanting  in 
this  respect  can,  however,  be  easily  added  for  any  latitude. 

Whether  the  amorphous  pulverulent  carbonate  of  lime, 
which  forms  the  body  of  the  asphalt  rock,  can  be  dispensed 
with  and  its  place  supplied  from  other  sources,  is  that 
branch  of  this  subject,  to  which  the  differences  of  opinion 
really  attach.  Until  quite  recently — say  within  the  last 
eighteen  months — the  writer  somewhat  mildly  took  the 
negative  of  this  question,  and  his  views  were  published  in 
a short  article  on  bitumen , in  Johnson’s  New  Universal 
Cyclopaedia.  But  the  success  of  certain  asphalt  pavements 
in  the  city  of  New  York,  notably  those  in  Fifth  avenue  near 
Twenty- fourth  street,  and  in  Eighteenth  street  oast  of  Fourth 
avenue,  leaves  no  doubt  in  his  mind  that  the  bituminous  lime- 
stone, and  the  mineral  tars  of  the  Jurassic  region  can  both  be 


WOOD,  STONE,  AND  ASPHALT  COMPARED. 


10? 


dispensed  with  in  the  future,  for  paying  purposes.  The  two 
pavements  referred  to  were  not  laid  upon  proper  foundations, 
but  directly  upon  the  old  block-stone  and  cobble-stone  pave- 
ments set  in  sand.  There  has  therefore  been  unequal  settle- 
ment in  the  foundations  to  some  extent,  to  which  the  sheet 
of  asphalt  has  conformed,  as  it  always  will.  In  other  respects, 
and  indeed  in  all  respects,  involving  the  merits  of  the  mate- 
rial in  question,  these  specimens  of  street  covering  compare 
favorably  with  the  asphalt-rock  pavements  of  Paris  and  Lon- 
don, with  which  the  writer  is  to  some  extent  familiar  both 
from  personal  examination,  and  from  the  written  reports 
of  experts. 

Comparative  merits  of  Wood,  Stone,  and  Asphalt 

Pavements. 

In  this  comparison  only  first-class  pavements  of  their 
kind  will  be  considered.  The  brick  pavement  described  on 
pages  168  and  169  is  omitted  for  want  of  sufficient  data  with 
regard  to  its  durability  and  cost.  The  asphalt  block  pave- 
ment, in  the  absence  of  direct  personal  knowledge  respect- 
ing its  several  merits,  is  also  omitted,  although  regarded 
with  great  favor. 

Durability. 

Assuming  the  foundation  to  be  firm  and  solid,  so  that 
ruts  and  depressions  cannot  form  upon  the  surface  except 
from  actual  wear,  a pavement  of  stone  blocks,  of  first  qual- 
ity as  regards  hardness  and  toughness,  will  possess  the  long, 
est  life  of  the  three,  and  one  of  wood  blocks  the  shortest  : 
asphalt  lies  between  the  two  and  very  near  to  the  stone,  and 
will  fluctuate  from  this  position  with  the  amount  and  kind  of 


198 


ROADS,  STREETS,  AND  PAVEMENTS. 


traffic,  and  the  influences  of  the  climate.  As  a rule  wood 
must  be  regarded  as  the  least  durable.  When  it  begins  to 
go— at  the  end  of  two  or  three  years,  under  heavy  traffic — it 
wears  rapidly  into  deep  and  numerous  ruts,  by  the  crushing 
of  the  blocks  to  their  entire  depth.  Unless  the  stone  be  of 
excellent  quality  for  pavements,  it  takes  the  second  place  in 
the  order  of  durability,  and  asphalt  the  first. 

First  Cost. 

The  absolute  cost  of  constructing  the  different  pavements 
will  of  course  vary  very  considerably  with  the  locality.  It  is 
believed,  however,  that  with  few  exceptions,  the  following 
order  of  cheapness  will  obtain  throughout  the  United  States  : 
viz.,  first,  wooden  blocks;  second,  asphalt,  on  a solid  cobble 
stone  foundation  ; third,  asphalt,  on  a concrete  foundation; 
fourth,  stone  blocks  on  a concrete  foundation. 

Cost  of  Maintenance  and  Repairs. 

Under  this  head  the  life  or  endurance  is  to  be  consid- 
ered, and  the  total  expense  must  extend  over  and  cover  a peri- 
od of  time  representing  that  endurance,  under  the  assump- 
tion that  at  the  end  of  that  period,  the  pavement  is  in  as  good 
a condition  as  at  the  beginning  when  it  was  new.  The  repairs 
for  the  first  two  or  three  years  will  be  comparatively  trifling, 
and  in  some  cities,  more  especially  in  England,  it  is  custom- 
ary for  the  constructor  to  maintain  the  pavements  in  a 
good  sound  condition  without  charge  for  one,  two,  and 
sometimes  three  years,  and  subsequently  for  a longer  period, 
seldom  exceeding  fifteen  years,  for  a specified  sum  per  square 
yard  per  year. 

With  regard  to  wood  and  asphalt,  the  recorded  observa- 


WOOD,  STONE,  AND  ASPHALT  COMPARED. 


195 


tions  make  it  certain  that  although  a pavement  of  wooden 
blocks  is  less  costly  to  construct  than  one  of  asphalt,  not  only 
is  its  annual  cost  for  repairs  greater,  but  its  mean  annual  cost 
during  its  life,  inclusive  of  the  first  cost,  is  also  greater  than 
that  of  asphalt.  With  regard  to  stone,  there  is  a vast  differ- 
ence in  the  endurance  of  hard  and  tough  basalt  or  trap,  and 
the  average  granite  and  gneiss. 

In  economy  of  maintenance  per  year  during  the  life  time 
of  a pavement,  including  its  first  cost,  the  hard  basaltic  trap 
rocks  should  be  placed  first,  asphalt  second,  and  wood  third, 
except  in  localities  where  wood  is  very  cheap  and  suitable 
stone  cannot  be  procured,  or  is  subject  to  heavy  charge  for 
transportation.  Under  such  circumstances  stone  would  take 
the  third  place  and  wood  would  rise  to  the  first.  Where 
wood  and  stone  are  both  expensive,  or  the  latter  is  not  of 
the  best  quality  with  respect  to  toughness,  asphalt  would 
take  the  first  position. 

Facility  of  Cleansing. 

Both  mud  and  dust  adhere  with  more  tenacity  to  wood 
than  to  asphalt  or  stone,  more  especially  after  the  fibres  of  the 
former  begin  to  crush  and  abrade,  and  the  order  of  merit  in 
this  respect  will  be  first  asphalt,  second  stone,  and  third 
wood,  whether  the  cleansing  be  done  by  sweeping  or  by 
washing.  It  stands  to  reason  that  a smooth,  even  surface 
can  be  cleansed  more  rapidly  than  one  cut  up  with  numer- 
ous joints. 

Convenience. 

Mr.  William  Haywood,  C.E.,  of  London,  in  his  report 
•‘as  to  the  relative  advantages  of  wood  and  asphalt  for  pav- 


200 


ROADS,  STREETS,  AND  PAVEMENTS. 


ing  purposes,”  made  to  the  commissioners  of  sewers  of  the 
city  of  London,  March  17th,  1874,  says  that  “asphalt  is  the 
smoothest,  driest,  cleanest,  most  pleasing  to  the  eye,  and 
most  agreeable  for  general  purposes,  but  wood  is  the  most 
quiet.”  It  might  perhaps  be  better  to  say  that  the  noise  pro- 
duced by  wood  is  of  a different  kind,  which  may  be  more 
disagreeable  to  some  persons  and  less  so  to  others.  Stone  is 
the  noisiest  of  all  pavements. 

The  noise  produced  by  wood  is  a constant  rumble,  that 
by  asphalt  an  incessant  clicking  of  the  horses’  feet  upon  the 
street  surface,  wdth  scarcely  any  noise  from  the  carriage 
wheels,  while  stone  gives  out  a deafening  din  and  rattle 
from  feet  and  vehicle  combined. 

On  the  supposition  that  the  surface  is  kept  clean  by 
either  sweeping  or  washing,  the  difference  in  slipperiness 
between  wood,  stone  that  does  not  polish  under  wear,  and 
asphalt,  is  not  great,  although  enough,  perhaps,  to  place 
asphalt  last ; while  a horse  not  only  falls  more  frequently, 
but  recovers  himself  less  often  and  less  easily  upon  it  than 
upon  the  others,  by  reason  of  the  joints  in  the  latter,  which 
give  a foothold.  When  the  surface  is  covered  with  mud, 
asphalt  is  the  most  slippery  of  the  three,  and  very  little  mud 
makes  it  slippery.  s It  cannot  be  said  to  be  slippery  when 
very  dry,  or,  if  free  from  mud,  when  very  wet. 

In  times  of  snow  there  appears  to  be  little  if  any  differ- 
ence in  this  respect  between  wood,  asphalt,  and  stone,  but 
under  a sharp  dry  frost,  asphalt  and  stone  are  generally  quite 
dry  and  safe,  while  wood  retains  moisture  and  is  very  slippery. 

In  the  condition  in  which  they  are  usually  maintained,  a 
slight  rain  adds  to  the  slipperiness  of  each  of  these  pave- 
ments, with  this  difference  that  on  asphalt  and  stone  this 


WOOD,  STONE,  AND  ASPHALT  COMPARED. 


201 


state  begins  with  the  rain  or  very  soon  thereafter,  while 
the  worst  condition  of  wood  ensues  later.  It  however  lasts 
longer  than  upon  the  others  on  account  of  its  absorbent 
nature.  With  regard,  therefore,  to  the  convenience  and 
comfort  of  those  using  the  street,  as  well  as  those  living 
adjacent  thereto,  the  weight  of  opinion  appears  to  place 
asphalt  first,  wood  second,  and  stone  third,  for  all  streets 
except  those  habitually  crowded  with  heavy  traffic,  in  which 
case  stone  would  rise  to  the  first  place  and  asphalt  drop  to 
the  third. 

Hygienic  Considerations. 

A practical  and  general  recognition  of  the  fact — so  well 
known  in  the  medical  profession,  and  indeed  among  all 
ranks  of  cultured  people — that  the  pavements  of  a city 
exert  a direct  and  powerful  influence  upon  the  health  of  its 
inhabitants,  has  never  been  secured.  Most  people  claim 
simply  that  a street  surface  should  be  hard  and  smooth  with- 
out being  slippery,  and,  as  a measure  of  economy,  that  it  shall 
be  durable  and  easily  cleansed  ; but  they  go  no  further. 

The  advantages  of  noiselessness  are  recognized  by  many 
upon  various  grounds  ; by  the  large  majority  as  simply  con- 
ducive to  comfort,  but  by  few  as  conducive  to  health  ; while 
the  kind  of  material  used,  provided  it  satisfies  the  foregoing 
conditions,  and  the  character  of  the  surface  is  satisfactory 
with  regard  to  continuity  and  impermeability,  is  far  too 
generally  considered  to  be  a matter  of  small  moment. 

The  hygienic  objections  to  granite,  are  first  its  constant 
noise  and  din,  and  second  its  open  joints  which  collect  and 
retain  the  surface  liquids,  and  throw  off  noxious  vapors  and 
filthy  dust. 

9* 


202 


ROADS,  STREETS,  AND  PAVEMENTS. 


In  populous  towns  there  is  scarcely  a moment  of  silence, 
night  or  day.  M.  Fonssagrives,  Professor  of  Hygiene  at 
Montpelier,  says,  K I cannot  consider  such  a perpetual  vibra- 
tion of  the  nerves  as  harmless  even  for  those  who  have  been 
born  and  bred  in  the  midst  of  the  noise.  It  is  certain  that 
it  is  a very  genuine  cause  of  erethism,  and  to  it  must  be 
ascribed  the  prevalence  of  nervous  temperaments  and  dis- 
eases in  the  large  towns.  . . I have  known  a young  girl 

of  seventeen  years  old,  suddenly  transported  from  the  prov- 
inces to  a noisy  quarter  of  Paris,  show  the  most  alarming 
symptoms  of  nervous  disorder,  which  did  not  subside  until 
she  returned  to  a quieter  and  less  exciting  atmosphere.  At 
the  periods  of  a woman’s  life  when  she  is  most  subject  to 
nervous  maladies,  this  danger  should  be  most  carefully 
guarded  against.  And  what  shall  we  say  of  the  nerves  of 
children  and  invalids  ? If  the  former  are  hard  to  rear  in 
cities  which  create  hysterics  at  eight  years  of  age,  some 
blame  must  certainly  be  laid  upon  the  air  they  breathe  and 
the  moral  conditions  in  which  they  have  been  educated  ; 
but  some  part  of  the  evil  must  be  attributed  to  the  influence 
exercised  by  noise  oil  these  little  beings,  in  whose  organiza- 
tion the  cerebral  predominance  is  the  most  marked  feature. 
As  for  invalids,  quiet  is  of  the  first  importance,  and  the 
noise  in  the  streets  is  the  cruelest  stumbling  block  in  the 
way  of  recovery.” 

Dr.  A.  M’Lane  Hamilton,  Assistant  Sanitary  Inspector 
of  the  city  of  New  York,  in  an  official  report  dated  October 
19,  1874,  says,  “A  quiet  and  noiseless  street  pavement 
would  advance  the  health  of  the  population  to  a great  extent. 
The  sufferer  from  nervous  diseases  would  find  relief  from 
the  noise  of  empty  omnibuses  and  wagons  rumbling  or  rat- 


HYGIENIC  CONSIDERATIONS. 


203 


I ling  on  the  rough  stones,  in  the  event  of  a removal  of  this 
tmisance.  In  fact  there  would  be  many  more  sanitary 
benefits  resulting  from  a change  than  I can  here  detail.” 

It  is  not  deemed  necessary  to  enlarge  further  upon  this 
point.  The  writings  of  eminent  medical  practitioners  are 
full  of  testimony  to  the  pernicious  influence  of  street  noise 
and  din  upon  the  health  of  the  population,  particularly  upon 
invalids  and  persons  with  sensitive  nerves. 

The  noisome  and  noxious  exhalations  emanating  from 
the  putrescent  matter,  such  as  horse-dung  and  urine,  col 
lected  and  held  in  the  joints  of  stone  pavements,  constitutes 
another  sanitary  objection  to  their  use  in  populous  towns. 
Exceptions  to  wood  may  be  taken  upon  the  same,  and  even 
upon  stronger  grounds,  for  the  material  itself  undergoes 
inevitable,  and,  sometimes,  even  early  and  rapid  decay,  in 
the  process  of  which  the  poisonous  gases  resulting  from 
vegetable  decomposition  are  thrown  off. 

The  joints  of  a block  pavement,  whether  of  wood  or 
stone,  constitute,  after  enlargement  by  wear,  fully  one- 
third  of  its  area,  and  under  the  average  care,  the  surface  of 
tilth  exposed  to  evaporation,  covers  fully  three-fourths  of 
the  entire  street.  This  foul  organic  matter,  composed 
largely  of  the  urine  and  excrement  of  different  animals,  is 
retained  in  the  joints,  ruts,  and  gutters,  where  it  undergoes 
putrefactive  fermentation  in  warm  damp  weather,  and  be- 
comes the  fruitful  source  of  noxious  effluvium.  In  dry 
weather  this  street  soil,  of  which  horse-dung  is  a large 
ingredient,  floats  in  the  atmosphere  and  penetrates  the 
dwellings  in  the  form  of  unwholesome  dust,  irritating  to 
the  eyes  and  poisonous  to  the  organs  of  respiration.  Its 
damage  to  furniture,  though  serious,  is  unimportant  in  this 


204 


ROADS,  STREETS,  AND  PAVEMENTS. 


connection.  In  the  side  gutters  and  underlying  soil  the 
foul  matter  exists  in  a more  concentrated  form,  the  supply 
being  constantly  renewed  from  the  crown  of  the  street,  and 
in  many  districts,  from  the  filthy  surface  drainage  of  back- 
ways  and  alleys  peopled  by  the  poorer  classes.  Is  it  too 
much  to  say  that  under  such  circumstances,  the  infant 
population,  and  especially  the  children  of  poor  people,  in 
large  towns,  can  only  be  reared  under  such  predispositions 
to  disease,  as  will  constitutionally  render  them  an  easy  prey 
to  epidemics  in  maturer  years  ? 

The  foregoing  are  some  of  the  leading  hygienic  objections 
to  pavements  laid  in  blocks,  whether  of  stone,  wood  or  other 
material.  There  are  others  peculiar  to  wood  alone  arising 
from  its  decay,  its  natural  porosity,  and  the  spongy  char- 
acter conferred  upon  it  by  wear  and  crushing. 

“ Impregnation  of  the  wood  with  mineral  matters,  to  pre- 
serve it  from  decay,  may  diminish  these  evils,  but  nothing 
as  yet  tried  prevents  the  fibres  being  separated,  and  the 
absorption  of  dung  and  putrescent  matter  by  the  wood 
being  continued.  The  condition  of  absorbing  mere  moist- 
ure is  of  itself  bad,  but  when  the  surface  absorbs  and 
retains  putrescent  matter,  such  as  horse-dung  and  urine,  it 
is  highly  noxious.  The*  blocks  of  pavement  with  this 
material  are  separated  by  concussion,  and  are  thus  rendered 
permeable  to  the  surface  moisture.  Mr.  Sharp,  who  exam- 
ined some  blocks  taken  up  for  re-pavement,  states  that  he 
found  them  perfectly  stained  and  saturated  with  wet  and 
urine  at  the  lower  portions,  while  the  upper  portions  were 
dry.  Mr.  Elliott,  a member  of  the  society,  and  for  many 
years  a deputy  of  the  Common  Council  of  the  city  of  London, 
has  carefully  observed  the  trials  of  new  modes  of  pavement 


HYGIENIC  CONSIDERATIONS. 


205 


there,  and  objects  to  the  wood  that  it  is  continuously  wet  and 
damj^.  ‘ Wood  is  porous  ; it  is  composed  of  bundles  of  fibres. 
It  absorbs  and  retains  wet,  foul  wet  especially.  The  fibres 
of  the  wood  are  placed  vertically,  the  upper  ends  whereof 
fray  out,  are  abraded  and  become  like  painters’  brush  stumps, 
and  are  almost  permanently  dirty,  or  they  break  like  the 
handle  of  a chisel  which  has  been  struck  with  an  iron  ham- 
mer or  wooden  mallet.’  This  fact  is  beyond  all  question. 
Wood  is  wet  or  damp,  more  or  less,  except  during  continued 
very  dry  weather.  Its  structure  is  admirably  adapted  to 
receive  and  hold,  and  then  give  off  in  evaporation,  very  foul 
matters,  which  taint  the  atmosphere  and  so  far  injure 
health.”  (Report  of  P.  Le  Neve  Foster,  Secretary,  Society 
for  the  Encouragement  of  Arts,  Manufactures,  and  Com- 
merce : London.  1873.) 

Physicians  assert  that  hospital  gangrene  frequently 
results  from  washing  the  wooden  floors  of  the  wards  with 
water,  and  that  on  shipboard,  new  or  moist  timber,  between 
decks,  impairs  the  health  of  the  sailors.  Fatal  epidemics  at 
sea  have  been  traced  to  timber  that  has  become  saturated 
with  putrescent  matter,  or  wet  with  bilge  water. 

Prof.  Fonssagrives,  of  France,  says:  “ The  hygienist  can- 
not, moreover,  look  favorably  upon  a street  covering  consist- 
ing of  a porous  substance  capable  of  absorbing  organic  matter, 
and  by  its  own  decomposition  giving  rise  to  noxious  miasma, 
which,  proceeding  from  so  large  a surface,  cannot  be  re- 
garded as  insignificant.  I am  convinced  that  a city  with  a 
damp  climate,  paved  entirely  with  wood,  would  become  a 
city  of  marsh  fevers.” 

The  dust  produced  by  the  abrasion  and  wear  of  a wooden 
pavement  is  regarded  by  physicians  as  extremely  irritating  to 


206 


ROADS,  STREETS,  AND  PAVEMENTS. 


the  organs  of  respiration,  and  to  the  eyes,  and  being  light 
in  weight,  it  floats  longer  in  the  atmosphere  and  is  carried 
to  a greater  distance,  than  that  from  any  other  suitable 
material  in  use  for  street  pavements. 

The  evidence,  from  a sanitarian  point  of  view,  against 
the  use  of  wood  for  paving  purposes  in  populous  towns,  is 
very  strong,  but  the  evils  are  not  developed  to  the  same 
extent  in  all  localities.  Decomposition  begins  in  two  or 
three  years  in  clayey  and  retentive  soils,  while  it  is  very 
considerably  retarded  and  the  wood  remains  habitually  drier 
and  emits  less  effluvia  where  the  subsoil  is  sandy  and  porous. 

The  most  characteristic  features  and  properties  of  asphalt 
pavement  have  been  briefly  summarized  on  page  176  and  it  is 
not  deemed  necessary  to  repeat  or  enlarge  upon  them  here. 
Professor  Fonssagrives  remarks  that,  “ The  absence  of  dust, 
the  abatement  of  noise,  the  omission  of  joints — permitting  a 
complete  impermeability  and  thus  preventing  the  putrid 
infection  of  the  subsoil — are  among  the  precious  benefits 
realized  by  asphalt  streets.” 

Upon  hygienic  grounds,  therefore,  asphalt  conspicuously 
stands  first,  stone  second,  and  wood  third,  in  order  of  merit. 

The  correct  inference  from  the  foregoing  discussion  is 
that  no  one  pavement  combines  all  the  qualities  most  desir- 
able in  a street  surface.  It  cannot  be  sufficiently  rough,  or 
sufficiently  soft,  to  give  the  animals  a secure  foothold,  and  at 
the  same  time  possess  that  smoothness  and  hardness  which 
is  so  essential  to  easy  draught.  The  advantages  of  open  joints 
and  entire  freedom  from  street  filth  cannot  exist  together, 
under  any  reasonably  cheap  method  of  cleansing  the  surface. 

A pavement  of  impermeable  blocks,  if  laid  upon  a solid 
Inundation,  may  be  constructed  and  maintained  in  a water 


general  deductions. 


207 


tight  condition,  by  thoroughly  calking  the  joints  with 
suitable  material,  leaving  the  surface  sufficiently  rough  and 
open  to  obviate  the  objection  to  a continuous  monolithic 
covering,  but  roughness,  combined  with  the  requisite  hard- 
ness, is  incompatible  with  the  freedom  from  noise  attainable 
with  some  kinds  of  acceptable  street  surface. 

In  order,  therefore,  to  obtain  the  best  pavement  for  any 
given  locality  a judicious  balancing  of  characteristic  merits  is 
generally  necessary.  The  best  pavement,  so  far  as  we  now 
know,  for  all  the  busiest  streets  of  a populous  city,  where  the 
traffic  is  dense,  heavy  and  crowded,  is  one  of  rectangular 
stone  blocks  set  on  a foundation  as  good  as  concrete,  or  as 
rubble  stone  filled  in  with  concrete ; and  the  next  best  is 
one  of  Belgian  blocks  set  in  the  same  manner. 

The  best  pavement  for  streets  of  ample  width,  upon 
which  the  daily  traffic  is  not  crowded,  or  for  streets  largely 
devoted  to  light  traffic  or  pleasure-driving,  or  lined  on 
cither  side  with  residences,  is  continuous  asphalt  for  all 
grades  not  steeper  than  1 in  48  or  50. 

If  the  blocks  of  compressed  asphalt  fulfill  their  present 
promise,  they  may  be  able  to  replace  those  of  stone  upon 
streets  where  the  latter  are  now  preferable  to  a sheet  of 
asphalt  on  account  of  the  steepness  of  the  grade. 

It  has  been  urged,  as  an  objection  to  a concrete  founda- 
tion, that  it  is  difficult  to  take  up  in  order  to  reach  the  gas  and 
water  pipes.  This  is  true  only  in  the  sense  that  good  work 
is  not  easily  taken  to  pieces.  But  such  a foundation  when 
torn  up  or  deranged  from  any  cause,  can  readily  be  restored 
to  its  former  condition,  and  the  pavement  relaid  upon  it 
with  all  its  original  smoothness,  firmness,  and  stability,  con- 
ditions which  do  not  obtain  with  any  kind  of  pavement  laid 
upou  a bed  of  sand  or  gravel, 


CHAPTER  VI. 


SIDEWALKS  AND  FOOTPATHS. 

Sidewalks  and  other  footpaths  are  usually  paved  with 
flagging^stone,  bricks,  wood  in  the  form  of  planks  or  blocks, 
or  some  variety  of  concrete  in  which  either  bitumen  or 
hydraulic  cement  is  the  binding  material.  Various  kinds 
of  artificial  stone  have  been  used  for  the  same  purpose. 
Most  of  the  pavements  above  named  are  so  well  known  as  to 
need  no  mention  here. 

Concrete  Footpaths. 

Concrete  footpaths  should  be  laid  upon  a form  of 
well  compacted  sand  or  fine  gravel,  or  a mixture  of  sand, 
gravel  and  loam.  The  natural  soil,  if  sufficiently  porous  to 
provide  thorough  sub-drainage,  will  answer. 

It  is  not  usual  to  attempt  to  guard  entirely  against  the 
lifting  effects  of  frost,  but  to  provide  for  it  by  laying  the 
concrete  in  squares  or  rectangles,  each  containing  from 
twelve  to  sixteen  superficial  feet,  which  will  yield  to  upheaval 
individually,  like  flagging  stones,  without  breaking  and  with- 
out producing  extensive  disturbance  in  the  general  surface. 
When  a case  arises,  however,  where  it  is  deemed  necessary  to 
prevent  any  movement  whatever,  it  can  be  done  by  under- 
lying the  pavement  with  a bed  of  broken  stone,  or  a mixture 
of  broken  stone  and  gravel,  or  with  ordinary  pit-gravel  con- 
taining just  enough  of  detritus  and  loam  to  bind  it  together. 


CONCRETE  SIDEWALKS. 


209 


In  high  latitudes  this  bed  should  be  one  foot  and  upwards  in 
thickness,  and  should  be  so  thoroughly  sub-drained  that  it 
will  always  be  free  from  standing  water.  It  is  formed  in 
the  usual  manner  of  making  broken  stone  or  gravel  roads, 
already  described,  and  finished  off  on  top  with  a layer  of 
sand  or  fine  gravel  about  one  inch  in  depth  for  the  concrete 
to  rest  upon. 

The  concrete  should  not  be  less  than  3^  and  need  rarely 
exceed  4 to  4|  inches  in  thickness.  The  upper  surface  to 
the  depth  of  £ inch  should  be  composed  of  hydraulic  cement 
and  sand  only.  Portland  cement  is  best  for  this  top  layer. 
For  the  rest  any  natural  American  cement  of  standard 
quality  will  answer.  The  following  proportions  are  recom- 


mended for  this  bottom  layer  : 

Rosendale  or  other  American  cement 1 measure. 

Clean  sharp  sand 2J£  “ 

Stone  and  gravel. 5 “ 


It  is  mixed  from  time  to  time  as  required  for  use,  and 
is  compacted  with  an  iron-shod  rammer,  in  a single  layer,  tc 
a thickness,  less  by  half  an  inch  than  that  of  the  required 
pavement. 

As  soon  as  this  is  done,  and  before  the  cement  has  had 
time  to  set,  the  surface  is  roughened  by  scratching,  and  the 
top  layer  composed  of 

1 volume  of  Portland  cement,  and 

2 to  2J£  volumes  of  clean  fine  sand, 

is  spread  over  it  to  a uniform  thickness  of  about  1 \ inches, 
and  then  compacted  by  rather  light  blows  with  an  iron-shod 
rammer.  By  this  means  its  thickness  is  diminished  to  half 
an  inch.  It  is  then  smoothed  off  and  polished  with  a 


210 


HOADS,  STREETS,  AND  PAVEMENTS. 


mason’s  trowel,  and  covered  up  with  hay,  grass,  sand,  or 
other  suitable  material  to  protect  it  from  the  rays  of  the  sun 
and  prevent  its  drying  too  rapidly. 

It  should  be  kept  damp  and  thus  protected  for  at  least 
ten  days,  and  longer  if  circumstances  will  permit ; and  even 
after  it  is  opened  to  travel,  a layer  of  damp  sand  should  be 
kept  upon  it  for  two  or  three  weeks  to  prevent  wear  while 
tender. 

At  the  end  of  one  month  from  the  date  of  laying,  the 
Portland  cement  mixture  forming  the  top  surface  will  have 
attained  nearly  one-half  its  ultimate  strength  and  hardness, 
and  may  then  be  subjected  to  use  by  foot  passengers  without 
injury. 

The  rammers  for  compacting  the  concrete  should  weigh 
from  15  to  20  pounds,  those  used  on  the  surface  layer  from 
10  to  12  pounds.  They  are  made  by  attaching  rectangular 
blocks  of  hard  wood  shod  with  iron,  to  wood  handles  about 
3 feet  long,  and  are  plied  in  an  upright  position. 

Certain  precautions  are  necessary  in  mixing  and  ram- 
ming the  materials,  in  order  to  secure  the  best  results. 
Especial  care  should  be  taken  to  avoid  the  use  of  too  much 
water  in  the  manipulation.  The  mass  of  concrete,  when 
ready  for  use,  should  appear  quite  incoherent  and  not  wet 
and  plastic,  containing  water,  however,  in  such  quantities 
that  a thorough  ramming,  with  repeated  though  not  hard 
blows,  will  produce  a thin  film  of  moisture  upon  the  surface 
under  the  rammer,  without  causing  in  the  mass  a gelatin- 
ous or  quicksand  motion. 

The  concrete  may  be  prepared  by  hand,  or  in  the  con- 
crete mixture  Fig.  64.  Equal  care  is  essential  in  mixing  and 
compacting  the  top  layer  of  Portland  cement  and  sand.  The 


CONCRETE  SIDEWALKS. 


211 


frnxing  should  be  so  thorough  that  each  grain  of  sand  will 
be  entirely  coated  with  a thin  film  of  plastic  cement,  with 
very  little  excess  of  cement  not  thus  disposed  of. 

A characteristic  property  of  this  mixture  when  properly 
and  uniformly  prepared,  is  that  it  does  not  assume  a jelly- 
like  motion  under  the  rammer.  Excess  of  water  must 
therefore  be  carefully  avoided.  The  cement  must  be  pre- 
cisely such  that  the  effect  of  each  blow  of  the  rammer  will 
be  distinct,  local,  and  permanent,  without  disturbing  the 
contiguous  material  compacted  by  previous  blows.  If  it  be 
too  moist  the  mass  will  shake  like  wet  clay  ; if  it  be  too  dry 
it  will  rise  up  around  the  rammer  like  sand.  In  either  case 
the  mass  cannot  be  suitably  compacted  by  ramming,  and 
would  therefore  be  comparatively  weak  and  porous  after 
setting. 

The  Portland  cement  and  sand  may  be  mixed  together 
by  hand  on  a mortar  bed,  but  that  process,  to  obtain 
thorough  and  uniform  manipulation,  would  be  tedious  and 
expensive.  A better  method  would  be  by  a cubical  box  of 
somewhat  smaller  dimensions  than  the  concrete  mixer 
referred  to  above.  A kind  of  trituration,  or  a grinding  and 
rubbing  process  of  mixing  gives  the  best  results.  This  may 
be  easily  and  inexpensively  secured  by  putting  in  the  box, 
with  the  cement,  sand,  and  water,  several  smooth  rounded 
pebbles  weighing  6 to  8 pounds  each.  After  the  batch  is 
emptied  out  upon  the  platform,  these  are  taken  out  for 
further  use.* 

* The  writer’s  previous  publications,  viz.,  “ Limes,  Hydraulic 
Cements  and  Mortars,”  and  “ Beton  Agglomere  and  other  Artificial 
Stones,”  give  full  details  on  this  branch  of  the  subject.  They  ar« 
published  by  D.  Van  Nostrand  New  York  City. 


212 


ROADS,  STREETS,  AND  PAVEMENTS. 


When  silieious  hydraulic  lime,  like  that  of  Teil,  France- 
can  be  procured  at  moderate  cost,  it  can  be  used  with  advan- 
tage to  replace  one-third  to  one-half  of  the  Portland  cement, 
care  being  taken  to  so  adjust  the  proportions  that  the  vol- 
ume of  paste  produced  by  mixing  and  tempering  the  cement 
and  lime  together,  shall  exceed  by  about  25  per  cent  the 
volume  of  voids  in  the  sand,  as  ascertained  by  the  water 
test. 

In  laying  concrete  footpaths  in  squares  or  rectangles,  the 
material  is  spread  and  rammed  between  stout  planks  set 
and  firmly  maintained  on  edge,  with  their  upper  edge  coin- 
cident with  the  surface  of  the  path,  every  alternate  square 
being  omitted  in  the  first  instance,  to  be  subsequently  filled 
in, — say  on  the  following  day — after  those  first  formed  have 
become  sufficiently  hard  to  sustain  without  injury,  the  ram- 
ming of  the  fresh  concrete  against  them.  To  prevent 
adhesion  between  the  squares,  the  edge  against  which  the 
new  material  is  placed  may  be  covered  with  whitewash,  or  a 
coat  of  oil.  A strip  of  felt,  muslin,  or  card  board  interposed 
between  the  squares  will  answer  the  same  purpose,  although 
this  device  is  covered  by  the  Schillinger  patent. 

One  advantage  of  this  kind  of  footpath,  over  that  formed 
in  a continuous  layer,  is  that  the  squares  can  be  taken  up  to 
get  at  water  and  gas  pipes,  and  then  replaced  without  injury. 
In  some  cases  it  may  be  advantageous  to  mould  the  squares 
under  s&eds,  and  then  lay  them  like  common  flagging-stones, 
after  they  have  become  sufficiently  strong  to  bear  handling 
and  transportation.  Three  weeks  will  generally  suffice  for 
this  purpose.  It  will  be  found  unadvisable  to  make  them 
larger  than  three  to  three  and  a half  feet  square. 

The  Schillinger  pavement  for  footpaths,  which  is  patented 


CONCRETE  SIDEWALKS. 


213 


in  respect  to  the  method  of  preventing  adhesion  between  the 
squares,  is  formed  substantially  after  the  manner  above  de- 
scribed, with  this  important  exception  and  defect,  that  the 
top  layer,  which  receives  all  the  wear,  instead  of  being  mixed 
with  very  little  water  and  compacted  by  ramming,  is  applied 
in  a plastic  condition  as  a coat  of  mortar.  It  is  therefore 
comparatively  deficient  in  hardness,  compressive  strength 
and  the  power  of  resisting  frost.  Its  want  of  compressive 
strength,  in  particular,  was  fully  proved  by  experiments  in 
1871,  recorded  in  the  volume  on  “Beton  Agglomere  and  Other 
Artificial  Stones,”  from  which  the  table  page  214  is  taken. 
It  shows  in  a marked  manner  the  superior  strength  of  a 
mixture  that  can  be  compacted  by  ramming  ; as  well  as  the 
superiority  of  Portland  to  Rosendale  cement. 

The  surface  layer  of  the  concrete  pavement  above  de- 
scribed, resembles  in  all  essential  respects  the  artificial  stone 
to  which  the  name  beton  agglomere  has  been  given  in  France, 
sometimes  known  as  beton  Coignet,  from  M.  Francois  Coignet 
of  Paris,  who  first  introduced  it.  In  France,  however, 
the  silicious  hydraulic  lime  of  Teil  replaces  the  Portland 
cement  to  a large  extent,  some  of  the  strongest  samples  of 
the  stone  having  been  made  with  1 measure  of  this  lime 
(slaked  and  in  powder)  f of  a measure  of  dry  Boulogne  Port- 
land cement,  and  4 measures  of  sand.  The  compressive 
strength  of  this  mixture,  when  21  months  old,  was  reported 
by  Mr.  P.  Michelot,  ingenieur-in-chief  des  Ponts  et  C>haussee 
to  be  7176  lbs.  per  square  inch  for  one  specimen,  and  7405 
lbs.  for  another.  The  specimens  were  rectangular  blocks  3^ 
inches  deep,  3 inches  long  and  2^  inches  wide. 


214 


ROADS,  STREETS.  AND  PAVEMENTS. 


Proportion  of  Sand  and  Cement 
by  Measure  (dry). 

How  Mixed. 

Crushing  strength 
of  Blocks  in  gross 
tons. 

Rosendale  cement,  no  sand 

Not  plastic. 

6.25 

do.  do.  do 

Plastic. 

0.90 

Portland  cement,  no  sand 

Not  plastic. 

24.55 

do.  do.  do 

Plastic. 

22.32 

Rosendale  cement,  1.  Sand,  1.2 

Not  plastic. 

2.67 

do.  do.  do. 

Plastic. 

0.45 

Portland  cement,  1 Sand,  1.7 

Not  plastic. 

24.10 

do.  do.  do. 

Plastic. 

8.92 

Rosendale  cement,  1.  Sand,  1.8 

Not  plastic. 

1.00 

do.  do.  do. 

Plastic. 

0.53 

Portland  cement,  1.  Sand,  2.55 

Not  plastic. 

12.50 

do.  do.  do. 

Plastic. 

8.47 

Rosendale  cement,  1.  Sand,  2.35 

Not  plastic. 

1.34 

do.  do.  do. 

Plastic. 

Went  to  pieces 
in  water. 

Portland  cement  1.  Sand,  3.4 

Not  plastic. 

8.00 

do.  do.  do. 

Plastic. 

6.25 

Rosendale  cement,  1.  Sand,  3.5 

Not  plastic. 

0.45 

do.  do.  do. 

Plastic. 

Went  to  pieces 
in  water. 

Portland  cement,  1.  Sand,  .5 

Not  plastic. 

4.46 

do.  do.  do. 

Plastic. 

2.23 

Rosendale  cement,  1.  Sand,  4.7 

Not  plastic. 

0.40 

do.  do.  do. 

Plastic. 

Went  to  pieces 
in  water. 

ASPHALT  FOOTPATHS. 


215 

The  table  gives  the  compressive  strength  of  blocks  3J 
inches  wide,  5^  inches  long,  and  3 inches  thick,  the  area 
under  pressure  being  19£  square  inches.  Some  of  the  blocks 
were  made  with  little  water  and  compacted  by  ramming, 
others  with  plastic,  rather  over-stiff  mason’s  mortar,  firmly 
pressed  into  the  moulds  with  a trowel.  The  Portland 
cement  was  made  at  Boulogne,  France.  The  blocks  were  7 
days  old,  having  been  kept  in  water  6 days. 

Asphalt  Footpaths. 

Asphalt  sidewalks  may  be  laid  after  either  of  the  two 
methods  described  for  pavements  for  carriage  ways,  but  the 
thickness  of  the  foundation,  if  of  concrete,  need  not  gener- 
ally exceed  3 to  4 inches,  and  that  of  the  asphalt  covering 
may  be  restricted  to  from  f to  \ or  at  most  f of  an  inch. 

In  compact  clayey  soils  the  foundation  should  rest  upon 
a lay  of  sand  or  gravel,  4 to  5 inches  in  thickness,  to  secure 
sub-drainage,  and  guard  against  upheaval  by  frost.  The 
various  patented  pavements  containing  coal  tar,  resin,  pitch, 
etc.,  will  generally  answer  as  a foundation  for  the  asphalt 
layer. 

Asphaljt  in  the  form  of  Bituminous  Mastic  is  also  used  for 
paving  sidewalks.  This  mastic  may  be  prepared  by  heating 
together,  In  a covered  iron  boiler,  mineral  tar  either  nat- 
ural or  manufactured,  (see  page  173  and  182)  and  certain 
calcareous,  silicious,  or  earthy  substances  previously  reduced 
to  powder,  and  it  differs  from  the  mixture  used  for  paving 
carriage  ways  only  in  containing  a little  more  of  the  min- 
eral tar. 

The  bituminous  mastics  of  Seyssel  or  Val  de  Travers  are 
prepared  by  mixing  the  bituminous  limestone  from  those 


210 


ROADS,  STREETS,  AND  PAVEMEKTS. 


localities,  previously  pulverized  by  grinding  or  by  roasting, 
with  the  mineral  tar  derived  from  the  impregnated  sand- 
stone. In  the  Seyssel  limestone  7 to  8 per  cent  of  tar  must 
generally  be  added,  while  that  from  Val  de  Travers  will 
seldom  require  more  than  4 to  5 per  cent  of  tar.  The  tar 
required  for  a given  quantity  of  mastic  is  first  heated  in  the 
iron  boiler,  until  the  liquid  begins  to  emit  a whitish  vapor. 
The  powdered  stone  is  then  added  little  by  little,  care  being 
taken  not  to  add  it  in  quantities  large  enough  to  cause  a 
sudden  lowering  of  the  temperature.  The  emission  of  a 
yellowish  or  brownish  vapor  indicates  too  high  a degree  of 
heat,  when  the  fire  must  be  reduced  and  the  mass  stirred 
rapidly,  to  prevent  injury  to  the  mastic  by  scorching. 

For  convenience  of  handling,  the  mastic  is  moulded  into 
blocks  measuring  about  20  inches  by  12  inches  by  6 inches. 
When  used  it  is  broken  up  into  small  fragments  and  re- 
melted, 2 to  3 per  cent  of  mineral  tar  being  then  added  to 
compensate  for  loss  at  the  second  heating. 

The  pulverization  of  the  bituminous  limestone  prepara- 
tory to  its  incorporation  with  the  mineral  tar  may  be  effected 
by  either  grinding  or  roasting. 

For  grinding  it  is  simply  broken  up  into  pieces  about  the 
size  of  a hen’s  egg  and  then  passed  through  any  ordinary 
mill.  The  grinding  can  best  be  conducted  in  cold  dry 
weather,  as  the  stone  is  then  less  liable  to  cake  in  the  mill. 

For  roasting,  the  stone  is  first  broken  up  as  for  grinding, 
and  then  gently  heated  in  a covered  iron  vessel,  accompanied 
by  constant  stirring  with  an  iron  instrument,  which  causes 
the  fragments  to  disintegrate  and  fall  into  a partially  cohe- 
rent powder. 

Bituminous  mastic  is  suitable  for  paving  sidewalks, 


MASTIC  SIDEWALKS. 


217 


cellars,  areas,  markets,  and  for  covering  walls  and  arches  to 
exclude  water,  and  prevent  leakage. 

It  is  extensively  used  in  fortifications  for  covering  the 
arches  of  gun-casemates  and  powder  magazines  before  the 
earth  covering  is  put  on.  When  employed  for  pavements  it 
should  be  laid  upon  a concrete  foundation  of  sufficient 
thickness  to  support,  without  settlement  or  other  disturbance, 
the  greatest  weight  likely  to  come  upon  it.  This  thickness 
will  therefore  depend  upon  the  character  of  the  underlying 
soil,  but  will  rarely  exceed  3 inches.  The  thickness  of  the 
mastic  covering  is  usually  f to  f of  an  inch.  It  is  applied 
by  spreading  it  while  hot  and  plastic,  with  a wooden  trowel 
or  spatula,  great  care  being  taken  to  form  a water-tight  junc- 
tion between  contiguous  strips.  Before  applying  the  mastic 
upon  hydraulic  concrete  the  latter  should  be  covered  with  a 
very  thin  slipped  coat  of  common  lime  mortar  ; just  enough 
to  make  it  smooth. 

As  bituminous  mastic  contains  more  of  the  mineral  tar 
or  asphaltic  cement  than  the  mixture  for  street  pavements 
heretofore  described,  it  is  softer  than  that  mixture,  at  the 
same  temperature,  and  is  never  used  for  paving  carriage 
ways,  or  where  it  will  be  subjected  to  the  continued  tread  of 
heavy  animals.  It  is  doubtful  whether  it  is  as  good  even  for 
sidewalks,  as  asphalt  applied  in  the  usual  way  by  ramming. 

Where  sidewalks  have  vaults  beneath  them,  it  is  impor- 
tant that  the  percolation  of  water  from  the  top  as  well  as 
from  the  side  walls  next  the  street  should  be  prevented. 
When  the  vaults  are  covered  with  arches,  a layer  of  bitu- 
minous mastic,  and  even  of  some  of  the  best  coal  tar  prepara- 
tions, properly  laid  over  the  arches  before  the  earth  filling 
is  put  on  will  prevent  leakage  from  the  top. 

10 


218 


ROADS,  STREETS,  AND  PAVEMENTS. 


Another  method  is  to  keep  the  arches  so  low  that  a 
monolithic  bed  of  cement  concrete,  rather  rich  in  good 
cement  mortar,  and  not  less  than  4 to  5 inches  in  thickness 
over  the  crowns  of  the  arches,  can  be  put  over  the  entire 
width  occupied  by  the  vaults  and  the  side  wall  next  the 
street,  the  top  surface  of  the  concrete  being  finished  with  a 
coat  of  rich  cement  mortar,  at  the  proper  height  and  slope 
to  receive  the  pavement. 

Another  method  still  is  to  omit  the  arches  altogether, 
and  span  the  entire  width  of  the  sidewalk  with  stone  plat- 
forms 8 to  10  inches  in  thickness,  of  which  the  outer  edges 
take  the  place  of  the  curb  stones,  and  the  top  surfaces  that 
of  the  side-walk  pavement.  These  platforms  fit  closely  to- 
gether at  the  edges,  which  are  calked  to  render  them  water 
tight,  and  they  may  rest  upon  intermediate  piers  or  columns, 
wherever  danger  is  apprehended  of  their  inability  to  support 
the  greatest  weight  which  may  be  placed  upon  or  moved 
over  them. 

The  vault  wall  next  the  street,  if  properly  constructed 
of  rich  cement  concrete  in  a monolith  15  to  18  inches 
thick,  will  exclude  the  water  perfectly.  If  of  brick  laid 
in  bituminous  mastic,  with  all  the  vertical  joints  compactly 
filled  with  the  same  material,  it  will  also  be  water  tight  if 
only  12  inches  in  thickness.  But  if  the  bricks  are  laid  in 
cement  or  lime  mortar,  the  exterior  face  of  the  wall  should 
be  coated  with  bituminous  mastic,  throughout  its  entire 
height,  special  care  being  taken  to  secure  a perfect  junction 
between  this  surface  and  the  roof  surface.  The  filling 
directly  against  this  wall  should  be  coarse  sand  or  gravel,  so 
that  any  water  from  the  side  gutter  will  promptly  run  off. 


FLAGGING  STONE  FOOTPATHS. 


219 


Brick  Footpaths. 

Brick  pavements,  if  laid  with  carefully  selected  hard-burnt 
crick,  make  very  good  footpaths  for  streets  devoted  mainly 
to  residences,  or  where  there  is  very  little  loading  or  unload- 
ing heavy  goods  at  the  curb.  The  bricks  should  be  laid  on 
their  edges,  with  their  longest  dimensions  directly  or  diag- 
onally across  the  walk,  upon  a form  of  well  compacted  gravel 
or  coarse  sand,  or  preferably  upon  a foundation  of  creosoted 
boards  firmly  bedded  with  a uniform  bearing  on  the  sand,  to 
the  required  inclination.  The  boards  prevent  the  unequal 
settlement,  almost  certain  to  ensue  if  they  are  omitted,  in 
consequence  of  the  narrow  bearing  surface  of  the  bricks. 

Flagging  Stone  Footpaths. 

Flagging  stones  laid  upon  a form  of  sand  or  gravel,  or 
lirectly  upon  the  natural  soil  when  light  and  porous,  form, 
probably,  of  all  the  materials  above  mentioned,  the  best 
sidewalk  pavement,  and,  all  things  considered,  give  the  most 
general  satisfaction,  where  they  can  be  procured  of  good 
quality  and  at  reasonable  cost.  The  North  (Hudson)  River 
blue  stone  flagging  has  for  many  years  been  in  extensive 
demand  for  this  purpose,  in  cities  and  towns  of  the  Atlantic 
States,  north  of  the  Carolinas,  located  upon  water  routes. 
It  is  strong,  hard,  and  durable,  does  not  polish  and  become 
slippery  under  wear,  and  resists  frost  and  does  not  break  from 
upheaval  by  it,  unless  unusually  broad  and  thin.  The  quar- 
ries yield  slabs  of  any  required  thickness  and  superficial  area. 

Broken  Stone  and  Gravel  Footpaths. 

A very  good  footpath,  suitable  for  parks,  and  for  the 


220 


HOADS,  STREETS,  AND  PAVEMENTS. 


sidewalks  of  country  roads  and  suburban  streets,  can  be 
made  with  broken  stone  or  gravel,  or  with  a mixture  of  the 
two,  applied  in  substantially  the  same  manner  and  to  about 
half  the  thickness  described  in  Chapter  III,  for  the  construc- 
tion of  road  coverings. 

After  the  footpath  bed  has  been  excavated  to  the  re- 
quired width  and  depth,  it  should  be  compacted  by  a gar- 
den roller  or  by  ramming,  unless  the  soil  be  sufficiently  firm 
without  it. 

If  the  soil  be  wet  and  clayey,  or  if  it  be  at  all  infested 
with  springs,  a tile  drain  of  1|  to  2 inches  bore  should  be 
laid  below  the  reach  of  frost,  under  the  centre  of  footpaths, 
other  than  sidewalks,  and  the  trench  filling  above  it  should 
be  a sandy  or  gravelly  mixture  that  will  allow  the  water  to 
percolate  freely  through  it.  The  subdrainage  of  sidewalks 
is  presumed  to  be  suitably  provided  for  in  connection  with 
that  of  the  roadway. 

The  lower  layer  of  material  to  the  depth  of  4 or  5 inches 
may  be  small  rubble,  or  field  cobble  stone,  or  the  refuse  of 
quarries,  and  of  inferior  quality.  After  it  is  put  in  place  a 
roller  or  rammer  may  be  passed  over  it,  and  the  interstices 
partially  filled  up  by  breaking  off  the  projecting  fragments 
with  a hammer  ; or  the  required  evenness  may  be  secured  by 
a second  thin  layer  of  smaller  stones.  A surface  of  suitable 
gravel,  2 inches  in  thickness,  applied  in  two  layers,  with 
the  necessary  raking,  sprinkling,  and  rolling,  completes 
the  walk.  The  surface  layer  should  be  of  small  screened 
gravel,  when  practicable. 

For  park  walks  the  transverse  form  of  the  surface  should 
be  convex,  and  the  sides  of  the  walk,  where  no  paved  side 
gutters  are  used,  should  be  sufficiently  high  to  discharge 


FABRIC  A.TION  OF  CONCRETE. 


221 


the  surface  water  upon  the  adjacent  turf.  In  some  cases  it 
will  suffice  to  take  up  the  sod  on  either  side  of  the  walk  for 
a width  of  2|  to  3 feet,  and  reset  it  in  the  form  of  a 
shallow  trench,  called  a sod-gutter,  provided  with  suitable 
outlets — covered  or  open  drains — at  the  lowest  levels,  for 
arrying  off  the  surface  water. 

If  it  be  found  that  the  surface  water  is  not  promptly 
conveyed  away  by  these  means,  or  if  it  injures  the  sod  by 
wearing  it  into  gullies,  the  walks  must  be  provided  with 
paved  gutters,  on  one  or  both  sides,  as  circumstances  may 
require.  A neat  and  durable  gutter  may  be  formed  of  small 
cobble  stones,  such  as  can  usually  be  found  in  gravel  pits. 

Where  an  area  embraced  by  a system  of  park  walks  is  not 
susceptible  of  easy  and  sightly  surface  drainage,  one  or  more 
main  covered  drains  should  be  constructed,  with  a sufficient 
number  of  branches  to  collect  the  water  from  grated  silt- 
basins  located  in  the  depressions  of  the  side  gutters.  The 
location  and  size  of  these  drains,  will  be  governed  by  the  con- 
figuration of  the  ground,  the  kind  of  soil,  and  other  circum- 
stances of  a special  and  local  character. 

The  extensive  use  of  hydraulic  cement  concrete  recom- 
mended in  this  volume  renders  it  proper  that  some  general 
directions  for  its  fabrication  should  be  given  for  the  informa- 
tion of  those  not  familiar  with  its  properties.  The  following 
is  condensed  from  the  fifth  edition  of  the  writer’s  work  on 
“ Limes,  Hydraulic  Cements,  and  Mortars.”* 

Hand-made  Concrete. 

Each  batch  of  mortar  or  concrete  should  correspond  to 
one  cask  of  the  cement.  In  mixing  it  by  hand  labor,  four 

* D.  Van  Nostrand,  Publisher,  23  Murray  Street,  New  York. 


222 


ROADS,  STREETS,  AND  PAVEMENTS. 


men  constitute  a gang  for  measuring  out  and  mixing  the 
ingredients,  who  proceed  to  the  several  steps  of  the  process  in 
the  fallowing  order  : 

First . The  sand  is  spread  upon  the  platform  in  a rec- 
tangular layer  about  two  inches  in  thickness. 

Second . The  dry  cement  is  spread  equally  all  over  the 
sand.  If  lime  be  used  as  one  of  the  ingredients,  it  should 
first  be  slaked  to  a powder  by  sprinkling,  and  then  mixed 
with  the  dry  cement,  before  the  latter  is  spread  over  the  sand. 

Third . The  men  place  themselves,  shovel  in  hand,  two 
on  each  side  of  the  rectangle,  at  the  angles,  facing  inwards. 
Furrows  of  the  width  of  a shovel,  are  then  turned  outward 
along  the  ends  of  the  rectangle,  until  the  whole  bed  is 
turned.  The  two  men  on  one  side  then  find  themselves 
together,  and  opposite  the  two  on  the  other  side,  having,  of 
course,  left  a vacant  space  transversely  through  the  middle, 
of  double  the  width  of  a shovel.  They  then  move  quickly 
to  the  ends  of  the  wide  furrow  and  turn  successive 
furrows  inward,  when  the  bed  occupies  the  same  space  that 
it  did  previous  to  the  first  turning.  The  turning  is  executed 
by  successively  thrusting  the  shovel  under  the  material,  and 
turning  it  over  about  one  angle  as  a pivot.  Each  shovel  thus 
moves  to  the  middle  of  the  bed,  where  it  is  met  by  the  one 
opposite,  when  each  man  moves  back  to  the  side,  in  dragging 
the  edge  of  the  shovel  over  the  furrow  he  has  just  turned. 

Fourth.  A basin  is  formed  by  drawing  all  the  material 
to  the  outer  edge  of  the  bed. 

Fifth.  The  water  is  poured  into  the  basin  thus  formed. 

Sixth.  The  material  is  thrown  back  upon  the  water, 
absorbing  it,  when  the  bed  occupies  the  same  space  that  it 
did  in  the  beginning. 


FABRICATION  OF  CONCRETE. 


223 


Seventh . The  bed  is  turned  twice,  by  the  process  above 
described.  If  required  for  mason’s  use,  the  mortar  is  heaped 
up,  to  be  carried  when  and  where  required.  If  for  concrete 
(the  mortar  occupying  the  rectangular  space  as  at  first). 

Eighth.  The  coarse  materials  (whether  broken  stone, 
bricks,  gravel,  shells,  or  a mixture  of  two  or  more  or  all  of 
them)  are  spread  equally  over  the  bed. 

Ninth.  A bucket  full  of  water  more  or  less  (depending 
on  the  quantity  of  stone,  their  absorbing  power,  and  the 
temperature  of  the  air)  is  sprinkled  over  the  bed. 

Tenth.  The  bed  is  turned  once  as  before,  and  then 
heaped  up  for  use.  The  act  of  heaping  up,  when  done  with 
care,  has  the  effect  of  a second  turning. 

The  time  consumed  in  making  a batch  of  concrete,  com- 
posed of  one  barrel  of  cement,  two  and  a half  to  three  barrels 
of  sand,  and  five  or  six  barrels  of  the  coarse  materials,  is  from 
twenty-five  to  twenty-eight  minutes.  An  experienced  gang 
of  first-rate  laborers  can  do  it  in  a little  over  twenty  min- 
utes. If  lime  be  added,  the  amount  of  sand  and  coarse 
materials,  and  the  time  required  for  mixing  are  proportionally 
increased. 


Mill-made  Concrete. 

Mill-made  concrete  possesses  sufficient  superiority  over 
that  manipulated  by  hand,  to  justify  the  expense  of  provid- 
ing suitable  power  and  machinery,  when  operations  of  con- 
siderable magnitude  are  to  be  carried  on.  The  more 
thorough  manipulation  secured  by  machinery,  enables  a 
smaller  proportion  of  the  cementing  substance  to  be  used, 
and  effects  a saving  in  the  cost  of  both  materials  and 
labor. 


6* 


224 


ROADS,  STREETS,  AND  PAVEMENTS. 


The  Cubical  Concrete  Mixer. 


This  mixer.  Fig.  64,  consists  of  a cubical  box  made  of 
hard-wood  plank  or  boiler  iron,  measuring  about  four  feet 
on  each  edge  in  the  interior,  rigidly  mounted  on  an  iron 


axle  passing  through  opposite  diagonal  corners.  It  is 
provided  with  a trap  door  about  two  feet  square,  close  to  one 
of  the  six  angles  farthest  from  the  axle,  for  charging  and 
emptying  the  box.  Eight  to  ten  revolutions  of  the  box, 


FABRICATION  OF  CONCRETE. 


225 


made  in  less  than  one  minute,  are  found  to  be  quite  sufficient 
to  produce  a thorough  incorporation  of  the  ingredients.  A 
small  steam  hoisting  engine,  which  may  be  used  for  other 
purposes  at  the  same  time,  furnishes  the  best  power  for  turn- 
ing the  mixer,  and  screw  gearing  is  probably  the  best  method 
of  applying  it. 

The  mixer  is  charged  through  a hopper,  by  means  of  a 
tub,  swung  from  a common  derrick  crane,  and  holding  just 
one  batch  of  concrete,  the  volume  of  which  should  not  exceed 
one-third  to  two-fifths  the  entire  capacity  of  the  box. 

The  crane  should  of  course  be  worked  by  the  same  power 
that  turns  the  box,  and  should  have  a sweep  reaching  from 
the  platform  where  the  materials  are  measured  to  the 
hopper. 

The  process  should  be  conducted  in  the  following  order  : 

First  and  Second , spread  the  sand  and  the  cementing 
material  upon  the  platform,  as  in  direction  for  hand -made 
concrete. 

Third . The  dry  materials  may  be  mixed  together  with 
shovels,  as  for  hand-made  concrete,  or  they  may  be  only 
partially  incorporated  by  long  teethed  rakes  passed  back  and 
forth  through  them  without  disturbing  the  position  of  the  bed. 

Fourth . Empty  the  coarse  materials  upon  the  bed  of 
sand  and  cement  and  spread  them  over  the  same,  not  neces- 
sarily with  much  care. 

Fifth . Dash  over  the  bed  the  requisite  quantity  of 
water,  in  such  manner  that  it  will  be  absorbed  by  the 
material,  and  not  run  off  upon  the  platform. 

Sixth.  Shovel  the  materials  into  the  tub,  taking  care 
that  each  shovel  full  shall  contain  a portion  of  each  of  the 
ingredients. 


226  ROADS,  STREETS,  AND  PAVEMENTS. 

Seventh . Empty  the  tub  into  the  box  and  set  the  latter 
in  motion. 

Eighth . After  ten  or  twelve  revolutions,  occupying 
about  one  minute,  stop  the  motion,  open  the  trap-door 
and  empty  the  mixed  concrete  into  the  tub,  so  that  it  can 
be  deposited  by  the  crane  in  some  convenient  spot  within  its 
sweep,  and  thus  be  out  of  the  way  of  the  succeeding  batch. 

It  will  generally  be  found  convenient  to  convey  the  con- 
crete to  its  allotted  place  in  wheel-barrows.  It  should  be 
compacted  with  rammers,  in  horizontal  layers  5 to  6 inches 
in  thickness,  uutil  all  the  coarse  materials  are  driven  below 
or  flush  with  the  general  surface. 

As  a rule  concrete  should  be  compacted  in  place  before 
the  cement  has  had  time  to  take  its  initial  set.  Where  the 
cement  contains  quicklime,  a delay  of  a few  hours  is  some- 
times necessary  to  allow  the  lime  to  become  thoroughly 
slaked. 


CHAPTER  VII. 


TRAMWAYS,  AND  STREET  RAILWAYS. 

A horse  can  draw,  upon  a good  stone  tramway,  a load 
11  times  as  great  as  lie  can  move  with  the  same  effort  and 
at  the  same  speed  upon  an  ordinary  gravel  road,  the  force 
of  draught  being  only  of  the  load  in  the  first  instance 
while  in  the  second  it  is  XV  Even  upon  a very  dry  and 
smooth  broken  stone  road — i . e . a macadamized  road  in  its 
best  condition — the  tractive  force  is  3^  to  4 times  as  great 
as  upon  a good  stone  tramway. 

The  marked  advantages  of  a hard  smooth  surface  for 
the  wheels  of  heavy  vehicles  to  move  upon  on  the  one  hand, 
and  the  comparatively  great  expense  of  providing  such  sur- 
faces on  the  other,  has  led  to  the  practice  in  some  localities  of 
restricting  the  width  of  the  wheel  tracks  to  what  will  simply 
suffice  for  the  convenient  use  of  the  several  kinds  of  vehicles 
upon  which  the  traffic  is  conducted,  while  the  rest  of  the 
roadway  is  finished  with  a less  costly  covering. 

A construction  of  this  kind  is  called  a tramway,  which 
consists  of  two  parallel  tracks  of  suitably  smooth  and  hard 
material  to  receive  the  wheels,  while  the  spaces  between 
ihem  on  which  the  animals  travel,  as  well  as  the  road  sur- 
face on  either  side,  is  paved  with  a different  material. 

The  wheel  tracks  are  usually  of  stone  ; occasionally  of 
wood  or  iron. 

As  tramways  are  intended  for  the  equal  and  common 


228 


ROADS,  STREETS,  AND  PAVEMENTS. 


use  of  all  classes  of  vehicles,  and  not,  like  street  railways,  foi 
the  exclusive  benefit  of  specially  constructed  cars  restricted 
to  one  kind  of  traffic,  their  construction  and  maintenance 
properly  belong  like  street  paving  to  the  municipality, 
rather  than  to  private  corporations.  They  possess  certain 
advantages  over  street  railways  in  being  adapted  to  every 
variety  of  traffic  and  vehicles,  with  entire  freedom  to  leave 
the  tram  when  needful  without  becoming  helpless  or  ineffi- 
cient, and  return  to  it  as  occasion  or  convenience  may  sug- 
gest. Stone  tramways  are  in  general  use  in  Southern 
Europe,  particularly  in  Turin,  Milan,  Verona,  and  many  of 
the  smaller  cities  and  towns  of  Northern  Italy. 

The  Italian  Tramways. 

The  Italian  stone  tramways  consist  of  two  parallel  lines 
of  granite  blocks  or  slabs,  each  slab  being  usually  about 
2 feet  in  width  transversely,  8 inches  in  thickness,  and  4 to 
6 feet  in  length.  The  blocks  are  laid  end  to  end  with  close 
joints.  The  clear  distance  between  the  two  lines  is  aboui 
2 feet  4 inches,  making  the  width  between  the  two  axes 
or  center  lines  4 feet  4 inches,  which  is  about  the  average 
width  between  the  carriage  wheels.  The  roadway  is  usually 
formed  with  a slight  inclination  from  the  sides  toward  the 
centre,  the  tramway  blocks  being  laid  to  the  same  inclina- 
tion, with  their  upper  surfaces  flush  with  the  road  surface 
on  both  sides. 

The  horse  track  between  the  blocks  is  therefore  the 
lowest  part  of  the  road.  It  is  paved  with  cobble  stones  from 
the  neighboring  streams,  forming  a shallow  concave  channel 
along  which  the  surface  water  flows  away  into  suitable  cross 

drains. 


TRAMWAYS. 


229 


The  wings  of  the  road  may  be  paved,  Macadamized, 
graveled,  or  left  as  earth  roads. 

The  foundation  for  these  Italian  trams  usually  consists 
of  a bed  of  screened  gravel  5^  to  6 inches  in  depth,  sur- 
mounted with  a 2 inch  layer  of  sand  in  which  the  granite 
blocks  are  set. 

The  road  bed  is  well  compacted  by  ramming  or  rolling 
before  the  gravel  is  spread,  and  this  is  also  watered  and 
rolled  or  rammed  in  the  usual  manner.  Sub-drainage  is 
provided  in  soils  which  require  it. 

The  surface  drainage  is  discharged  by  the  central  gutter 
between  the  trams,  into  sub-drains,  through  vertical  shafts 
covered  with  stone  gratings.  The  gratings  are  formed  from 
a single  piece  of  granite,  cut  concave  on  the  top  to  corre- 
spond to  the  surface  between  the  trams,  and  usually  provided 
with  three  slots,  each  about  12  inches  long,  1-J  inches  wide, 
and  8 to  10  inches  apart. 

The  cost  of  constructing  one  mile  of  the  tramway  above 
described,  with  wages  varying  from  3 to  3^  francs  per  day 
for  stone  cutters,  1^  to  2 francs  for  common  laborers,  and 
2 francs  for  pavers,  amounts  to  about  $8, 600,  gold.  This 
includes  the  paving  between  the  trams,  the  subdrains,  and 
the  openings  in  the  central  gutter  leading  thereto  covered 
with  granite  gratings,  and  surface  grooving  the  blocks 
to  give  horses  a foothold  on  the  trams  when  turning  out 
on  steep  grades.  It  does  not,  however,  include  the  cost  of 
paving  the  roadway  outside  the  trams. 

Although  the  first  cost  of  a good  stone  tramway  is  com- 
paratively large,  it  possesses  a long  life,  and  the  necessary 
annual  expense  upon  it  for  repairs  is  but  a mere  trifle.  It 
is  an  error  to  assume  that  they  are  out  of  date,  although 


230 


ROADS,  STREETS,  AND  PAVEMENTS. 


their  usefulness  and  their  general  adaptation  to  the  necessi- 
ties and  conveniences  of  traffic,  have  been  greatly  restricted 
by  the  introduction  of  steam  and  street  railways.  They 
are  certainly  not  adapted  to  the  most  crowded  streets  of  a 
city,  and  afe  a connecting  route  between  neighboring  towns, 
a railroad,  although  costing  three  to  four  times  as  much, 
might  in  most  cases  be  preferable  ; but  upon  wide  streets 
and  over  short  suburban  lines  with  a large  traffic,  and  in 
special  cases  in  manufacturing  and  mining  districts,  and  in 
large  cities,  as  a connecting  link  between  the  termini  of 
railroads,  where  steam  cars  are  inadmissible,  they  are  able 
to  supply  a convenient  and  inexpensive  method  of  carriage, 
while  the  current  outlay  for  maintenance,  which  amounts 
to  a heavy  tax  upon  all  other  kinds  of  roads,  is  only 
nominal. 

Where  the  haulage  is  heavy  both  ways  the  tramway 
should  have  a double  track,  the  centre  line  of  blocks  being 
common  to  both,  and  wide  enough  to  allow  the  vehicles  to 
meet  and  pass  each  other  without  leaving  the  trams. 

To  insure  a greater  degree  of  permanence  and  stability, 
the  blocks  should  be  bedded  in  hydraulic  mortar,  upon  a 
concrete  foundation  6 inches  thick.  This  would  allow  a 
reduction  in  their  thickness  to  about  6 inches. 

The  horse  track  should  be  paved  with  stone  blocks  as 
greatly  preferable  to  cobble  stones. 

An  excellent  substitute  for  a stone  tramway  is  a stone 
block  pavement  of  carefully  selected  blocks  laid  in  mortar 
upon  a concrete  foundation.  Its  width  for  the  vehicles  in 
common  use  need  not  exceed  13^  to  14  feet  to  enable  them 
to  meet  and  pass  each  other  without  collision.  It  should  be 
along  the  middle  of  the  roadway,  and  slope  each  way  from 


STREET  RAILWAYS. 


231 


the  crown  at  the  rate  of  about  1 in  40,  the  wings  being  fin- 
ished with  any  covering  suitable  for  the  neighborhood. 

Tramways  should  of  course  be  laid  on  the  grade  of  the 
street  as  usually  constructed,  and  there  can  be  no  advantage 
in  having  the  middle  of  the  street  lower  than  the  sides. 

Street  Railways  (Called  also  Tramways). 

On  a well  built  railroad,  the  force  required  to  move  a 
car  upon  the  level  rail,  at  a speed  of  5 miles  per  hour  is  not 
far  from  to  sttt  of  the  total  weight  of  car  and  load,  vary- 
ing  within  these  limits  with  the  state  of  the  rail  with  respect 
to  moisture  and  dryness. 

The  following  rule  is  the  one  in  common  use  for  obtain- 
ing this  resistance  : 

1.  Multiply  the  weight  in  gross  tons  by  6.  The  pro- 
duct regarded  as  pounds  will  be  the  friction. 

2.  Multiply  the  weight  by  the  velocity  in  miles  per  hour 
and  divide  by  3.  The  quotient  will  be  the  allowance  to  be 
made  for  concussion,  in  pounds. 

3.  Square  the  velocity  in  miles  per  hour,  and  multiply 
the  square  by  the  frontage  in  feet,  and  divide  the  product 
by  400  for  the  resistance  of  the  atmosphere  in  pounds. 

4.  The  sum  of  these  three  results  is  the  total  resistance 
in  pounds. 

Upon  street  railway  lines,  in  consequence  of  the  presence 
at  all  times  of  more  or  less  dust  and  stiff  mud  upon  the 
rails,  the  tractive  force  is  comparatively  large.  In  the  average 
condition  of  the  road  it  may  be  set  down  as  fully  of  the 
loaded  car,  so  that  a car  weighing  4,000  lbs.  carrying  2S 
passengers,  each  weighing  150  lbs — total  8,200  lbs — would 
require  the  exertion  of  a force  of  68J  lbs  (-yVo0-)  to  move  it 


m 


ROADS,  STREETS,  AND  PAVEMENTS. 


on  a level  rail  at  a low  speed.  Upon  descending  grades  of 
1 in  68£  the  brakes  would  not  therefore  have  to  be  applied. 

In  practice  the  grades  must  conform  to  those  of  the 
street,’  and  for  short  lengths  maybe  even  steeper  than  would 
be  suitable  for  ordinary  vehicles  upon  a good  street  surface. 
The  question  of  grades,  therefore,  for  street  railways,  except 
in  special  cases,  resolves  itself  into  the  adoption  of  those 
already  existing. 

Upon  the  Bleecker  street  and  Fulton  Ferry  line,  in  New 
York  city,  there  are  two  very  steep  grades,  one  with  an 
aggregate  rise  of  10.3  feet  in  225.25  feet,  equal  to  a mean 
of  1 in  21.8,  and  the  other  with  an  aggregate  rise  of  10.3 
feet  in  248.8  feet,  equal  to  a mean  of  1 in  24.  The  point  of 
highest  grade  upon  each  ascent  is  very  considerably  steeper 
than  the  average  rise,  which  includes  those  portions  with  a 
gentle  grade  near  the  foot  and  the  crest  of  each  stretch. 

Drainage. 

Upon  streets  suitably  provided  with  paved  carriage  ways 
and  sidewalks,  and  with  sewers,  there  is  no  occasion  to  make 
any  special  or  additional  provision  for  the  drainage  of  street 
railways,  but  for  lines  located  upon  country  or  suburban 
roads,  the  same  precautions  must  be  taken  to  secure  thorough 
surface  and  sub-drainage  that  have  already  been  described 
as  necessary  for  ordinary  roads.  There  is  no  occasion  to 
’epeat  them  here. 

Construction. 

A street  railway,  as  almost  universally  constructed  in  the 
United  States  and  elsewhere,  consists  of  rolled-iron  rails, 
laid  upon  longitudinal  timbers  or  stringers,  resting  upon 


THE  RAILS. 


233 


timber  cross  ties.  The  top  of  the  rails  should  set  flush  with 
the  surface  of  the  street,  and  they  should,  preferably,  be  of 
such  patterns  and  laid  to  such  gauge  as  will  least  incommode 
the  ordinary  traffic  conducted  with  the  vehicles  of  the  neigh- 
borhood, for  it  will  rarely  occur  that  the  interests  of  the  rail- 
way, and  those  of  the  truck,  cart,  and  express  wagon  will  be 
other  than  identical.  Upon  crowded  streets  in  particular, 
and  generally  in  the  business  portions  of  cities  and  large 
towns,  every  device  calculated  to  keep  the  current  of  traffic 
moving,  and  prevent  blockades,  is  a benefit  alike  to  all. 

Rails. 

It  is  desirable  that  the  car  wheels  should  bear  upon  the 
rail  directly  over  the  centre  line  of  the  stringers,  or  as  nearly 
so  as  possible,  in  order  to  obviate  any  tendency  of  the  rail  to 
cant  to  one  side,  when  the  wood  begins  to  become  soft  and 
weak  from  decay.  This  condition  however  would  exclude 
the  rail  with  the  single  rib,  raised  on  one  side  only  (See 
Figs.  68  and  69)  and  having  a broad  flat  surface  occupying 
the  rest  of  its  width,  which  is  really  the  form  offering  the 
least  interference  with  the  traffic  conducted  on  ordinary 
carriages  ; for  the  broader  the  surface  upon  which  such 
carriages  can  track,  the  less  will  be  the  difficulty,  and  the 
less  the  wrench  upon  the  wheels,  as  well  as  upon  the  rails, 
in  taking  and  leaving  it. 

In  some  cities  the  pattern  of  the  rail,  as  well  as  gauge 
of  the  track,  is  prescribed  by  municipal  authority,  with 
special  reference  to  obtaining  such  a railway  as  will  not 
only  reduce  to  a minimum  the  annoyance  occasioned  by  the 
rails  to  promiscuous  traffic,  but  will  enable  them  even  to 
contribute  to  its  promotion  and  convenience. 


234 


llOAftS,  STEEETS,  AND  PAVEMENTS. 


A grooved  rail,  as  a general  rule,  is  not  the  most  desirable 
either  for  the  railway  company,  or  the  ordinary  vehicles  upon 
the  street.  It  collects  the  dust  and  mud,  and,  in  cold 
weather,  gets  filled  with  ice  and  snow,  thus  greatly  augment- 
ing the  tractive  force  of  the  car  ; while  the  wheels  of  wagons 
and  hacks,  and  especially  of  all  of  the  lighter  and  frailer 
classes  of  carriages,  having  once  entered  the  grooves,  experi- 
ence a severe  strain,  and  are  not  unfrequently  twisted  off,  in 
leaving  them,  while  the  rails  themselves  are  thereby  more  or 
less  disturbed  and  in  time  loosened  at  Wieir  fastenings.  In 
Fig.  65,  serviceable  and  convenient  forms  are  shown  at  b, 


7>.  b. 


4 


Fig.  65. 

which  if  made  of  55  pounds  weight  per  yard  will  answer  for 
heavy  traffic.  For  light  traffic. form  c of  30  to  35  pounds 
weight  has  been  found  to  be  suitable.  Rails  are  sometimes 
made  of  70  and  even  75  pounds  weight  to  the  yard.  Oast 
iron  rails  have  been  tried  without  giving  satisfaction. 

Stringers,  or  Sleepers. 

The  purpose  of  the  stringers  is  two-fold  : to  secure  a 
uniform  bearing  for  the  rails,  and  to  raise  them  to  the  level 
of  the  street  surface.  They  may  be  of  southern  or  of  ordi- 
nary white  pine,  preferably  the  former,  on  account  of  its 
superior  stiffness  and  hardness.  Any  other  kind  of  durable 


CkOSS  TIES. 


235 


frood  possessing  these  qualities,  may  of  course  be  used, 
provided  its  price  be  such  as  not  to  exclude  it.  Tli6 
sleepers  are  sawed,  the  usual  dimensions  being  7 to  8 inches 


Fig.  66. 


in  depth,  with  a width  equal  to  that  of  the  rail,  and  a length 
varying  from  25  to  40  feet.  (See  Figs.  66  and  67.) 

Cross  Ties. 

The  cross  ties  (Fig.  66)  may  be  of  any  durable  wood, 
either  white  or  yellow  pine,  chestnut,  or  white  oak,  hewn  oi 
sawed,  6 to  7 inches  wide,  5 to  6 inches  deep,  and  of  such 


Fig.  67. 


length  as  to  reach  about  12  inches  beyond  the  stringers  on 
either  side.  They  may  be  faced  on  the  top  and  bottom 
only,  the  bark  alone  being  taken  from  the  sides. 

Upon  streets  suitably  sub-drained,  the  cross  ties  are 
simply  laid  in  trenches  excavated  to  receive  them,  care  be* 


236 


ROADS,  STREETS,  AND  PAVEMENTS. 


ing  taken  not  to  loosen  up  the  soil  to  a greater  depth  than  is 
requisite  to  give  them  a firm  and  level  bearing  throughout 
their  entire  length,  with  their  top  surfaces  parallel  with  the 
line  of  the  grade.  The  earth  should  be  packed  around 
them  and  under  their  edges  by  tamping  with  a crow-bar  or 
other  suitable  implement,  to  guard  against  subsequent 
settlement  or  disturbance. 

When  suitable  sub-drainage  has  not  been  provided,  as 
will  often  be  the  case  upon  suburban  streets  and  country 
roads,  and  especially  where  the  railway  is  to  rest  upon 
clayey  or  spongy  soils,  the  bed  should  be  sub-drained,  in 
substantially  the  same  manner  prescribed  for  ordinary  roads, 
by  excavating  to  a width  exceeding  the  length  of  the  cross 
ties  by  at  least  some  inches,  and  to  a depth  of  6 inches 
below  them.  The  trench  thus  formed,  after  suitable  cross 
drains  have  been  constructed,  is  then  to  be  filled  in  with  a 
ballast  of  broken  stone,  gravel,  coarse  sand,  or  a mixture  of 
them  all,  which  should  be  thoroughly  compacted  by  ram- 
ming in  layers,  to  guard  against  further  settlement  or  shrink- 
age. When  the  filling  has  reached  the  requisite  height  to 
receive  the  cross  ties  these  are  placed  in  position,  the 
material  under  their  edges  further  compacted  by  tamping, 
and  the  filling  continued  to  the  level  of  their  top  surfaces. 

The  cross  blind-drains  should  be  at  least  12  to  18  inches 
in  depth,  below  the  bottom  of  the  filling  or  ballast,  and 
should  extend  out  on  either  side  to  the  side  ditches. 

To  preserve  them  from  early  decay,  the  stringers  and 
cross  ties  should  be  creosoted,  in  the  manner  described  ou 
page  162  which,  if  thoroughly  done,  will  add  at  least  ten 
years  to  their  life. 


FASTENINGS. 


23? 


Fastenings. 

No  little  difficulty  has  been  experienced  in  firmly  secur- 
ing the  rails  to  the  stringers,  and  the  stringers  to  the  cross 


ties,  and  no  system  or  method  of  fastenings  has  yet  been 


238 


ROADS,  STREETS,  AND  PAVEMENTS. 


devised,  possessing  so  few  objectionable  features  as  to  com- 
mand  general  adoption.  It  lias  been  found  impossible  to  do 
away  with  the  use  of  spikes,  bolts,  or  pins,  and  these  be- 
come loose  from  the  gradual  enlargement  of  the  holes  occa- 
sioned by  incessant  vibration. 

For  securing  the  stringers  to  the  cross  ties,  square  or 
octagonal  oak  or  locust  pins  have  been  used,  and  they  possess 
the  advantage  that  the  spikes  for  fastening  the  rails  can  be 
driven  into  the  pins,  in  cases  where  they  happen  to  come 
directly  over  them.  Half  inch  round  iron  bolts,  or  long  half 
inch  square  spikes,  are  generally  preferred  to  wooden  pins. 
The  ends  of  the  stringer  with  an  iron  plate  under  them,  should 
rest  on  a cross  tie,  and  not  fall  between  them,  but  those  on 
opposite  sides  should  not  meet  on  the  same  tie. 

To  prevent  the  spreading  of  the  track,  cast  iron  knees 
or  angle  irons  are  spiked  to  the  stringer  and  to  each  tie  or 
each  alternate  tie.  In  some  cases  these  knees  are  placed  on 
both  sides,  in  others  on  the  outside  only  of  each  stringer, 
(see  Fig.  68).  Transverse  wrought  iron  tie  bolts,  of  about  \ 
inch  round  iron,  passing  through  both  stringers,  and  having  a 
head  on  one  end  and  a screw  and  nut  on  the  other,  have  also 
been  used  for  the  same  purpose  either  with  or  without  the 
knees.  Such  ties  should  be  placed  near  the  bottom  of  the 
stringers,  in  order  that  they  may  receive  no  injurious  ten- 
sion or  strain  from  the  sinking  of  the  pavement  above  them. 

Additional  security  against  spreading  may  be  given  by  a 
good  block  stone  pavement,  upon  the  entire  street,  including 
the  space  between  the  rails,  provided  the  stones  be  set  firmly 
against  the  stringers  on  either  side.  Even  where  a cheaper 
kind  of  pavement  is  used  for  both  horse  track  and  street,  it 
is  desirable  that  one  row  at  least  of  stone  blocks  should  bo 


FASTENINGS. 


239 


set  on  each  side  of  each  stringer,  and  these  should  be  com- 
posed of  alternately  long  and  short  blocks  (as  shown  in  Fig. 
09),  so  as  to  tooth  into  the  contiguous  pavement,  and  thus 
avoid  a continuous  joint  which  would  wear  into  a rut. 

The  best  pavement  between  the  rails,  and  upon  which 
the  animals  appear  to  travel  with  greater  confidence  and  less 
fatigue  than  upon  any  other  possessing  the  requisite  firmness 


Fig.  69. 


and  durability,  is  one  of  rather  small  cobble  stones,  laid  with 
a very  slight  inclination  from  the  centre  toward  the  rails. 

The  top  of  the  pavement  should  be  at  the  same  height  as 
the  top  of  the  adjacent  edge  of  the  rail.  With  a rail  there- 
fore, having  a single  rib  on  one  side  and  a single  horizontal 
flange  on  the  other,  the  pavement  next  the  rib  will  be  a3 
much  higher  than  that  next  the  flange  as  the  rib  projects 
above  the  flange.  If  the  rib  be  on  the  inside  of  the  rail  the 


240 


ROADS,  STREETS.  AND  PAVEMENTS. 


horse  track  will  be  higher  than  the  rest  of  the  street,  and  if 
on  the  outside,  it  will  be  lower. 

Many  methods  of  fastening  the  rails  to  the  stringers  have 
been  practiced,  among  which  that  of  clinch  spikes  with 
countersunk  heads,  driven  vertically  through  the  bed  or 
thin  portion  of  the  rail,  well  into  the  sleeper,  is  about  the 
best.  When  the  width  of  the  bed  will  admit  of  it,  the 
spikes  should  be  placed  two  to  three  feet  apart,  alternately 
near  its  inner  and  its  outer  edges,  so  as  to  give  the  rail  a 
firmer  seat,  and  counteract  its  tendency  to  cant  to  one  side 
or  the  other.  Sometimes  the  spikes  pass  through  the  edge 
of  the  rail  diagonally,  and  sometimes  screws  are  used  diago- 
nally or  vertically.  When  rails  with  vertical  webs  at  the 
sides,  reaching  some  distance  down  the  faces  of  the  stringer, 
are  used,  the  fastenings  may  be  spikes,  screws,  or  staples 
passing  through  the  rail  into  the  timber  horizontally. 
The  ends  of  the  rails  should  meet  as  far  as  possible  from  the 
ends  of  the  stringers. 

The  perishable  nature  of  wood  is  a source  of  serious 
expense  in  the  maintenance  of  street  railways,  and  efforts 
have  been  made  to  substitute  iron  and  stone  for  the  timber 
cross  ties  and  sleepers,  but  no  trial  of  this  method  of  con- 
struction has  extended  over  a sufficient  period  of  time  to 
fully  test  its  practical  value. 

Many  experimental  attempts  have  been  made  to  replace 
horses  by  mechanical  motive  power,  for  the  propulsion  of 
street  cars ; and  gas,  hot  air,  electricity,  as  well  as  steam, 
have  been  suggested  and  some  of  them  tried  as  motors,  but 
never  with  entirely  satisfactory  results.  In  the  present  con- 
dition of  the  problem,  the  great  desideratum  appears  to  be 
a small,  noiseless,  spark-and-smoke-consuming  steam  engine. 


CAR  BRAKE  AND  STARTER. 


241 


Car  Starters. 

The  frequent  baitings  and  startings  which  are  necessarj 
for  the  accommodation  of  passengers  using  street  cars, 
operate  as  a most  serious  tax  upon  the  endurance  of  the 
horses,  and  within  the  last  few  years  many  mechanical  devices 
have  been  tried,  mostly  as  matter  of  experiment,  with  the 
object  of  removing  or  lessening  this  evil. 

The  prevailing  idea  appears  to  have  been  to  store  up  the 
power  necessarily  exerted  by  the  brakes  in  bringing  the  car 
to  a state  of  rest,  by  the  compression  of  some  form  of  spring, 
and  then  to  expend  it  in  turning  the  car  wheels,  so  as  to  assist 
the  horses  at  the  moment  they  are  required  to  start  forward. 

It  is  to  be  regretted,  however,  that  no  car  starter  has  yet 
been  invented,  possessing  sufficient  practical  merit  to  com- 
mand general  approval.  They  have  all  failed  in  a greater 
or  less  degree,  to  render  with  reasonable  certainty,  and  at 
the  proper  moment,  the  measure  of  aid  required  of  them. 
In  order  to  be  efficient,  they  should  be  under  the  easy  and 
quick  control  of  the  driver,  and  possess  enough  initial  power 
to  move  the  car  within  1 to  1^  seconds  after  the  signal  to 
start  is  given,  and  before  the  horses  have  taken  the  draught 
upon  their  collars. 

The  principle  upon  which  the  Crozier  car  brake  and 
starter  operates  will  be  understood  from  Fig.  70.  The 
upper  portion  of  the  figure  represents  the  apparatus  in  plan, 
while  an  end  view  is  given  in  the  middle,  and  a side  view  in 
the  bottom  cut. 

A is  a bevel  wheel  keyed  fast  to  the  car  axle,  and  B is 
another  wheel  facing  it  but  fitted  so  as  to  turn  and  slide 
on  the  axles  and  having  a rose  clutch,  C,  for  connecting  to 


242 


ROADS,  STREETS,  AND  PAVEMENTS. 


the  axle  so  as  to  turn  it  when  desired  ; it  also  has  a sleeve 
D,  extending  nearly  to  wheel  A,  and  coupled  by  a crotched 
arm  E,  with  a rock  shaft  below  (seen  at  F in  the  bottom 
cut)  by  which  the  driver,  by  means  of  a lever  at  W,  shifts 
the  gears  as  required  for  stopping  and  starting. 

The  sleeve  D,  is  also  the  bearing  for  one  end  of  the 
shaft  G,  on  which  is  a wheel  I,  for  gearing  with  wheel  A, 
also  a wheel  H,  for  gearing  with  wheel  B,  and  also  a drum 
K,  for  winding  up  a spring  or  springs  L,  and  which  has 
its  other  bearing  in  the  arm  J,  of  the  rock  shaft  F,  so  that 
by  the  oscillation  of  the  rock  shaft  through  the  medium 
of  the  lever  at  W,  the  shifting  is  effected. 

When  the  car  is  moving  forward,  if  the  driver  by  a move- 
ment of  the  lever  at  W,  gears  the  shaft  G,  with  the  wheel  A, 
by  means  of  the  wheel  I,  the  drum  K winds  up  a chain  which 
compresses  the  spring  L until  the  car  stops,  the  wheel  B being 
at  this  time  disconnected  with  the  clutch  0,  and  free  to 
move  around.  At  the  signal  to  start,  the  shaft  G is  thrown 
out  of  gear  with  the  wheel  A,  and  the  wheel  B at  the 
same  movement  engages  with  its  clutch  at  C.  The  spring 
then  reacts,  and  in  unwinding  the  chain  from  the  drum 
K,  starts  the  car  through  the  medium  of  the  wheels  H and 
B.  The  wheel  B,  being  larger  than  wheel  A,  affords  a 
greater  leverage  to  the  power  of  the  spring  in  starting,  than 
that  applied  in  compressing  it  when  stopping. 

The  Fireless  Locomotive. 

Upon  the  subject  of  mechanical  motive  power  for  street 
cars,  to  which  reference  was  made  on  page  240,  it  seems 
proper  to  mention  an  invention  of  Dr.  Lamme  of  New 
Orleans,  consisting  of  a small  locomotive  with  a boiler  of 


X 


J.B. POWER. St. N.Y 


Fig.  70, 


211  ROADS,  STREETS,  AND  PAVEMENTS. 

about  60  cubic  feet  capacity,  but  without  any  furnace  or 
other  appliance  for  heating  it. 

The  principle  upon  which  it  is  expected  to  work  may  be 
stated  briefly  as  follows  : 

“ When  required  to  start  the  car,  the  boiler  is  nearly 
filled  with  cold  water,  and  the  locomotive  is  run  alongside 
of  a large  stationary  boiler,  working  at  a pressure  of  200  lbs. 
The  steam  pipe  of  the  stationary  boiler  is  connected  with  the 
locomotive  boiler,  steam  then  rushes  into  the  latter,  and  in 
a few  minutes  it  raises  in  the  cold  fireless  boiler  a pressure 
of  180  lbs.  The  connection  with  the  stationary  boiler  is  then 
uncoupled,  and  the  fireless  locomotive  is  ready  for  work.” 

The  experiments  which  were  made  with  this  fireless 
engine  were  tolerably  successful  on  roads  that  were  level  or 
had  only  very  low  grades,  and  while  there  were  very  few 
stoppages ; but  upon  steep  grades  and  when  operating  with 
frequent  halts,  its  limited  power  was  soon  rendered  inefficient 
by  the  constant  loss  of  heat  by  radiation. 

As  street  railways  must  adopt  the  ordinary  grades  es- 
tablished for  other  vehicles,  and  as  the  stoppages  must  neces- 
sarily be  frequent  to  allow  passengers  to  get  in  and  out,  and 
must  be  made,  even  upon  ascending  grades,  unless  they  are 
exceptionally  steep,  Dr.  Lamme’s  locomotive  will  require 
extensive  modification  and  improvement  before  it  can  be 
accepted  as  a practical  solution  of  this  question. 

There  are  such  strong  prejudices  in  the  mind  of  the  gen- 
eral public  against  placing  a steam  boiler  in  a car  occupied 
by  passengers,  even  although  it  may  be  kept  entirely  out  of 
sight,  and  so  arranged  as  not  to  interfere  with  their  comfort 
or  convenience,  that  it  is  doubtful  whether  a self-contained 
gteam  car  can  ever  commend  itself  to  popular  favor. 


STATISTICS  OF  STREET  RAILROADS. 


245 


It  is  to  be  hoped,  for  the  benefit  of  all,  that  the  inventors 
who  do  not  share  this  view,  will  be  able  by  mechanical  con- 
trivance and  skill,  to  remove  the  objections  on  which  it  is 
founded. 

Statistics  of  Street  Railroads. 

The  following  tables,  giving  the  chief  particulars  of 
certain  horse  railway  companies,  have  been  arranged  at  the 
request  of  the  author,  by  Mr.  Isaac  Newton,  Engineer,  of  New 
York  city,  from  the  annual  reports  of  the  Massachusetts  Rail- 
way Commissioners,  and  the  State  Engineer  and  Surveyor  of 
the  State  of  New  York  for  1873.  The  examples  have  been 
selected  so  as  to  give  information  respecting  the  operation  of 
such  railways  in  the  crowded  streets  of  cities,  as  well  as  on 
ordinary  country  roads  or  turnpikes. 

The  particulars  given  may  be  divided  in  two  classes  : first 
those  regarding  the  cost  of  the  construction  of  the  roads  : 
second,  those  referring  to  the  cost  of  maintenance,  including 
all  operating  expenses,  and  the  amount  and  source  of  the 
revenue.  In  the  case  of  the  New  York  railways,  the  figures 
respecting  the  cost  of  construction  are  not  in  all  cases  reliable, 
but  those  regarding  the  operating  expenses  are,  in  the  opinion 
of  the  writer,  correct : the  latter  are  obviously  of  the  most 
importance.  Engineers  can  estimate  with  all  needful 
accuracy  the  cost  of  constructing  and  equipping  a proposed 
horse  railway  ; but  respecting  the  cost  of  operation,  the  facts 
obtained  from  experience  with  existing  roads  are  the  only 
safe  guides  to  a close  estimate. 

Regarding  the  Massachusetts  Roads,  both  classes  of 
figures  may  be  taken  with  confidence,  as  accurate  statements 
of  the  facts. 


246 


ROADS,  STREETS,  AND  PAVEMENTS. 


TABLE  I. — Particulars  of  Horse  Bailroads  in  State  of  New  York , 


I.  Description  of 
Road, 

1.  Length  laid 

2.  Length  of  double 
track,  incl.  sidings. 

L Weight  of  rails, 
pounds  per  yard. . . 

II,  Revenue, 

1.  From  passengers. . 

2.  Horses,  manure, 

old  material,  adver- 
tising in  cars,  and 
miscellaneous 

3.  Total  revenue. 

III,  Ope  rating 
particulars. 

1.  Number  of  passen- 
gers carried 

2.  Rate  of  fare 

8.  Rate  of  speed,  in- 
cluding stops.... 

IV,  Equipment 

1.  No.  horses  or  mules 

2.  Number  of  cars... 

V,  Cost  of  Road 
and  Equipment. 

1.  Road-bed  super- 
structure, incl.  iron, 

2.  Land,  buildings,  & 

fixtures,  incl.  land 
damages 

3.  Horses  & harness. 

L Cars 


Second 

Avenue 

Railroad. 


10  miles. 

11  miles. 
60  lbs.... 

$678,547 

$2,637 

$681,185 

13,570,955 

( 6c. thro, 
'j  5c. way. 

1 h.  20  m. 

1022 

154 

$1,816,412 

$410,593 

$173,187 

$111,550 


Third 

Avenue 

Railroad 


8 miles. 
10  “ 

56  to  681b  s 

$1,512,396 

$628,429 

$2,140,826 

26,950,000 

j 6c. thro. 

| 5c.  way. 

1 h.  20  m. 
1841 

( 251  Pas. 
"j  llFrt. 

$1,500,000 

$1,817,365 

$250,000 

$190,000 


Sixth 

Avenue 

Railroad. 


4 miles. 
4.375  “ 

60  lbs. 

$737,357 

$201,07; 

$938,434 

14,747,141 
•j  5 cents. 

6 m.  p.  h. 
1,097 

j-  100 

$857,444 

$827,590 

$385,817 

$111,108 


B’way 
and  7th 
Av.  R.  R. 


8 miles. 
16.25  m. 
52,62,65  lbs 

$894,188 

$25,97; 

$920,158 

17,883,776 
5 cents. 

46  min. 

1,146 

141 

$2,841,270 

$657,360 

$191,050 

$157,478 


Eighth 

Avenue 

Railroad. 


9,50  m. 


60to65  lbs 
$757,152 

$40.88? 

$798,040 

15,143,048 
5 cents. 

90  min. 

1,000 

110 

$844,459 

$599,211 

$102,390 

$137,513 


Dry  Dock 
and  East 
B’way 
Railroad. 


10.73  m. 


48,52,62  lbs 


$776,808 


f Bonds 
‘ $490,900 
Mis., 
$7,915 

$1,275,623 


15,536,160 
5 cents. 


835 

131 

$340,241 

$474,831) 

$141,775 

$134,000 


STATISTICS. 


24? 


compiled  from  Report  of  N.  Y.  State  Engineer  and  Surveyor  for  1873. 


42d  and 
Grand  St. 

Ferry 
Railroad . 

Bleecker 
St.  and 
Fulton  F. 
Railroad. 

Ninth 

Avenue 

Railroad. 

Brooklyn 
Bath  and 
Coney  Is. 
Railroad. 

Brooklyn 

City 

Railroad. 

Brooklyn 
City  and 
Newtown 
Railroad. 

Coney  Is. 
and 

Brooklyn 

Railroad. 

Buffalo 

Street 

Railroad 

Company 

J. 

1. 

5.13  miles 

9 miles. 

6.10  miles 

7 miles. 

40.50  m. 

15  miles. 

10.20  m. 

8.81  in 

2. 

3. 

5.13  miles 
64  lbs. 

13  miles. 
56  lbs. 

3,000  ft. 
45to70  lbs 

41  miles. 

7lA  miles. 
45&52  lbs. 

4.63  m. 
45  lbs. 

8.81  m. 
50  lbs. 

62to95  lbs 

45to64  lbs 

n. 

1. 

$340,637 

$252,859 

$89,217 

$50,577 

$1,461,303 

$191,955 

$179,924 

$200,920 

f Boiids, 

] 

2. 

j $236,000 
1 Mis., 

1 $10,119 

[ $4,864 

$6,486 

$15,322 

$34,990 

$5,231 

$41,96? 

$123,349 

3. 

$586,757 

$257,704 

$95,704 

$65,900 

$1,496,294 

$197,186 

$221,891 

$324,269 

TIT. 

1 

6,812,759 

5,057,191 

1,784,346 

386.234 

29,500,000 

3,886,314 

3,506,117 

3,442,768 

2 

5 cents. 

5 cents. 

5 cents. 

( Adults, 
< 5,  8,  10. 
( Ch.3&  4 

[ Adits.  5 

( Thro. 25 
Way, 

( propor. 

j-8  cents. 

1 Ch.3  cts 

3. 

IV . 

57  min. 

40  min. 

47  min. 

Kfk 

1 h.  46  m. 

45  min. 

5U  mm. 

1. 

444 

400 

190  ■{ 

1 horse,  9 

{•  1,895 

301 

281 

dum.  cars 

2. 

58 

40 

20 

j 24  Pass. 

J-  412 

68 

j 

58  cars. 

1 2 Frt. 

1 

14  sleighs 

F. 

1. 

$729,754 

$1,749,554 

$515,786 

$69,890 

$1,090,855 

$216,814 

2. 

$171,510 

$28,523 

$443,122 

$48,164 

$600,543 

• $813,273 

- $698,806 

$160,464 

3. 

4. 

$93,959 

$59,455 

Extens’n, 

$23,595 

$22,600 

$17,600 

$127,993 

j- $733,401 

$71,216 

248 


ROADS,  STREETS,  AND  PAVEMENTS. 


Second 

Third 

Sixth 

B’way 

Eighth 

Dry  Dock 
and  East 

Avenue 

Avenue 

Avenue 

and  7th 

Avenue 

B’way 

Railroad. 

Railroad. 

Railroad. 

Railroad. 

Av.  R.  R. 

Railroad. 

VI.  Operating 

Expenses . 

1.  Repairs  to  road-bed 

rlw.,  incl.  iron,  rep. 
of  hidings,  fixtures, 

$22,497 

( $131,975 
■l  Rl.  Est. 

j.  $110,255 

$41,469 

$47,390 

$49,691 

( $220,281 

2.  Taxes  on  real  est. . 

$3,900 

§25,128 

$22,781 

$14,875 

$22,852 

$8,839 

3.  Superintend.,  office 

exp.,  clerks,  etc.... 

$22,209 

$44,675 

$12,476 

$18,850 

$20,261 

$22,359 

4.  Conductors  & driv. 

$146,089 

$341,116 

$170,136 

$194,052 

$162,111 

1 

5.  Watchmen,  start- 

f $239,993 

ers,  switchmen,  and 
roadmen 

$29,160 

$224,983 

$49,320 

$18,875 
( Snow — 

$15,274 

) 

J 

f Engine, 

i $1,508 

6.  Repairs  of  cars  — 

$23,608 

$49,633 

$23,616 

i $8,157 

[ $46,524 

1 Cars. 

( $30,516 

) 

1 $45,795 

7.  Repairs  of  harness, 

$3,764 

$8,885 

$5,749 

$4,989 

$6,709 

$4,994 

8.  Horseshoeing 

$24,500 

$60,768 

$39,727 

$28,020 

$29,096 

$22,674 

9.  Horses  or  mules. . . 

$28,302 

$131,628 

$106,337 

$48,600 

$63,200 

$49,114 

10.  Stable  expenses.. 

$59,362 

$8,493 

$71,539 

$63,501 

$57,376 

$3,202 

11.  Feed,  hay,  etc 

$119,820 

$267,144 

$150,780 

$154,404 

$137,298 

$138,611 

12.  Fuel,  gas,  & lights 

$6,149 

$18,747 

$6,732 

$8,577 

$7,080 

$5,556 

13.  Oil  and  waste 

$501 

$2,750 

$818 

$1,311 

$755 

$850 

14.  Water  tax,  ins’ce. 

J $915 

\ $3,438 

j-  $4,762 

$8,253 

$4,85j 

$5,220 

j $1,091 
\ $7,607 

15.  Law  expenses  — 

$2,476 

$22,746 

$2,150 

$4,954 

$6,997 

$2,442 

16.  Damages  to  per- 

$7,419 

sons  and  property. 

$5,118 

$2,294 

$1,763 

$6,264 

$2,220 

17*  'Rp.nt.s 

$1,899 

$19,150 

$4,000 

$3,500 

$328 

$9,927 

$5,250 

$375 

$9,812 

18  Car  licenses  - . - - 

19.  Advert,  and  print. 
20  Taxes  on  divid’ds 

$4,751 

$67 

$487 

$174 

( Snow — 

21.  Contingencies 

22.  Total  operating 

$7,358 

$1,600 

$4,216 

$3,364 

$2,550 

$648,476 

8 $10,21.' 

( $3,931 

$634,990 

expenses 

$511,073 

$1,591,516 

$794,484 

$655,709 

STATISTICS. 


249 


42d  and 
Grand  St. 

Ferry 

Railroad. 

Bleecker 
St.  and 
Fulton  F. 
Railroad. 

Ninth 
Avenue 
Railroad . 

Brooklyn 
Bath  and 
Coney  Is. 
Railroad. 

Brooklyn 

City 

Railroad. 

Brooklyn 
City  and 
Newtown 
Railroad. 

VI. 

1. 

$9,019 

$4,121 

$6,956 

$15,101 

$61,879 

1 

[ $4,648 

2. 

$14,770 

$4,657 

$382 

$49,433 

J 

3. 

$15,511 

$7,427 

$3,762 

$4,486 

$38,869 

$5,250 

4. 

$67,359 

$49,549 

$28,109 

$3,065 

$387,120 

] 

l $62,727 
1 

5. 

$20,116 

$7,053 

$3,691 

$3,427 

$69,383 

J 

6. 

$17,419 

$20,119 

$3,320 

$2,939 

$53,816 

- $7,852 

7. 

$2,302 

$2,551 

$79: 

$11,306 

8. 

$10,656 

$10,991 

$4,182 

$50,600 

9. 

$20,300 

$44,471 

$1,300 

$365 

$45,874 

$9,448 

10. 

$30,622 

$22,415 

$8,874 

$104,027 

11. 

$50,097 

$35,838 

$22,752 

$245,313 

$36,033 

12. 

$2,338 

$1,541 

$739 

$2,753 

$8,360 

$935 

13. 

$43 

$484 

$104 

$661 

$627 

$103 

14. 

$1,583 

$1,932 

$1,352 

$1,139 

$9,365 

$1,526 

15. 

$4,250 

$390 

$330 

$3,000 

$50 

16. 

$1,£88 

$633 

$448 

$16,781 

$318 

17. 

$1,500 

$6,022 

$150 

$2,328 

$401 

18. 

$400 

19. 

$20 

$9 

$55 

$34 

$2,389 

20 

21. 

$24,410 

$4,453 

$108 

$834 

$29,620 

$1,769 

22. 

$293,709 

$220,007 

$91,942 

$35,340 

$1,190,098 

$131,064 

Coney  Is. 
and 

Brooklyn 

Railroad. 


$15,141 

$1,346 

j $3,000 
1 $2,901 


| $54,286 


$12,790 

$1,560 

$5,683 

$10,322 

$13,784 

$34,338 

$1,158 

$271- 

$3/1 

$654 

$600 

$237 


$624 


$4,034 

$155,862 


Buffalo 

Street 

Railroad 

Company 


$21,945 


$45? 
j-  $10,706 
$47,959 


$13,784 

$2,720 

$7,684 

$18,935 

$27,836 

$23,881 

$1,879 

$261 

$2,794 

$1,456 

$528 


$3,019 


$9,010 

$194,862 


250 


ROADS,  STREETS,  AND  PAVEMENTS. 


TABLE  II. — Giving  'particulars  of  the  horse  railways  nam,ed  below 
compiled  from  the  report  of  the  Board  of  Raihcay  Commissioner .1 
of  the  State  of  Massachusetts  for  1873. 


Highland 
St.  R’lwy 

Lynn  and 

Lowell 

Merimac 

Metropoli 
tan  Street 

Boston 

Horse 

Valley  Hse. 

Boston. 

Railway. 

Railway. 

R’lwy  Co. 

R.’lway  Co. 

I.  Description  of  Road 

5.42 

11.75 

.13 

3.815 

5 

43.608 

8.734 

2.  Length  of  double  track. 

3.  Length  of  single  track 

1.985 

l | 

operated  in  one  direc- 

1.17 

5.091* 

4.  Length  of  single  track  in 

both  directions,  miles. 

.28 

11.61 

3.815 

5 

21.043 

5.  Length  of  switches,  sid- 

ings  etc.,  miles. 

.25 

.87 

.216 

1600  feet 

3.981 

6.  Length  measured  as  sin- 

gle track,  miles 

5.67 

12.61 

4.031 

5.303 

47.589 

7.  Weight  of  rail  per  yard,  \ 
pounds f 

.48 

% = 45  1 

28  XA  to  33 

1600  ft. =19 
10400  ft.  =30 

j-  30  to  55K 

II.  Equipment. 

1.  No.  of  horses  or  mules. . 
2 Number  of  cars 

252 

36 

239 

35 

50 

12 

55 

15 

1269 

201 

III.  Cost  of  Construc- 

tion. 

1 Grading  and  Paving 

$124,591 

$14,006 

$2,000 

2.  Track,  including  timber, 

rails,  and  laying 

37,211 

35,784 

3,  Engineering  and  other 

exp.  during  construction, 
4 Total  cost  of  constructs 

14,950 

139,541 

238 

$181,960 

51,455 

37,784 

*1,100,437 

5.  Average  per  mile  of  sin. 
track,  not  incl.  sidings  . . 

25,745 

15,485 

13,487 

7,556 

25,232 

IV.  Cost  of  Equipment 

1 Horses  or  mules 

38,870 

41,605 

32,265 

30,300 

8,002 

12,002 

9,327 

16,618 

165,819 

189,956 

2.  flnrs 

$.  Other  vehicles  and  arti 

cles  of  equipment.... 

16,686 

16,698 

4,757 

5,165 

112,420 

STATISTICS. 


251 


Highland 
St.  R’lwy, 
Boston. 

Lynn  and 
Boston 
Railway. 

Lowell 

Horse 

Railway. 

Merrimac 
Valley  Hse. 
R’lwy  Co. 

Metropoli- 
tan Street 
R’lwy  Co. 

V.  Operating  Ex- 
penses. 

1.  Reps,  of  rd.-bed  & tracks 



$15,767 

$1,845 

$2,507 

$47,915 

8.  Reps,  of  cars  and  other 
vehicles,  harness,  horse- 

shoeing.. 

$6,175 

19,164 

3,751 

5,419 

39,732 

3 Repairs  of  buildings. . . . 

1,588 

70 

338 

6,940 

4.  Keeping  good  the  stock 

of  horses  

5.  Wages  of  all  employees. 

1,950 

9,439 

439 

29,464 

excepting  Pres.,  Treas., 

Sup’t/  and  clerks . . 

60,893 

55,716 

11,677 

11,853 

431,225 

6.  Provender 

25,896 

31,397 

10,066 

8,485 

158,338 

7.  Taxes  and  insurance 

2,312 

1,729 

865 

900 

24,900 

8.  Damages  for  injuries  to 

person  and  property 

32 

11.562 

782 

31,970 

9.  Rents  & tolls  paid  other 

companies 

18.402 

12,013 

5,051 

181,823 

3,019 

117,673 

10.  Salaries,  office  exp.,  etc. 

11.  Interest 

5,960 

3,068 

4,245 

12.  Total  exp.  of  operating. 
VI.  Eevenue. 

103,920 

32,127 

34,188 

891,220 

1.  Received  from  pass’gers. 

127,399 

162,713 

33,555 

34,002 

945,585 

2.  Rec.  from  sale  of  manure 

609 

1,301 

638 

520 

2,219 

3.  Inc.  from  other  sources. 

255 

531 

sm 

26,048 

4.  Total  income 

128,008 

164,269 

34,724 

34,845 

982,853 

5.  Pr.  ct.  of  exp.  to  income, 

92.5 

110.68 

92.5 

98. 

90.676 

VII.  Operating  Parti- 
culars. 

1.  No.  miles  run  by  cars... 

397,432 

447,068 

122,953 

176,280 

2,470,214 

2.  Aver,  cost  per  mile,  cts. 

26.12 

40.67 

26.1 

19.4 

36,018 

3.  No.  of  pass’gers  carried. 

2,511,180 

2,150,652 

592,716 

453,673 

18,211,026 

1 Rate  of  speed,  incl.  stops. 

Miles  per  hour 

6 

6 

5 

5 

5 to  6 

5.  No.  of  persons  regularly 

employed  by  Company  . . 

149 

102 

25 

24 

640 

6.  Rate  of  fare — cents.,  -j 

6ct.  ticket 
5 

j-  4 to  25 

4,  5,  and  6 

3 

5 to  15 

* This  is  the  total  cost  to  the  Company  of  road  built  and  purchased ; the  cash 
cost  is  estimated  to  be  $1,046,473.79. 


252 


ROADS,  STREETS,  AND  PAVEMENTS. 


The  Brooklyn  City  Railroad  Company  operates  41  miles 
of  double  track,  radiating  from  the  Fulton  and  Hamilton 
Avenue  ferries  through  the  city  to  its  suburbs  in  various 
directions.  The  returns  for  the  year  1875,  show  that  the 
company  owns  1,950  horses.  Each  working  horse  travels, 
upon  an  average,  16^-  miles  daily,  which  somewhat  exceeds 
the  average  daily  distance  traveled  on  the  New  York  city 
lines.  The  monthly  feed  bill  amounts  to  about  $19,000. 

During  the  year  1875  the  company  lost  334  horses,  and 
the  yearly  depreciation  in  the  value  of  the  live-stock  was  about 
28  per  cent.,  the  average  annual  depreciation  for  a term  of 
years  being  about  25  per  cent.  The  number  of  men  em- 
ployed is  1,000. 

The  company  carried  during  the  year  29,000,000  passen- 
gers, at  an  average  cost  per  passenger  of  4T2^r  cents,  or  ar 
aggregate  cost  of  $1,221,592. 

The  gross  receipts  from  passengers  were  $1,446,537. 

Mr.  Sullivan,  the  President,  states  that  among  the  vari- 
ous pavements  in  use  between  the  rails,  upon  the  ten  roada 
operated  by  his  company,  the  one  which  is  the  easiest  upon 
the  horses,  and  therefore  the  best,  is  formed  of  small  cobble 
stones,  laid  with  only  a slight  fall  from  the  centre  to  the 
sides ; and  that  the  horses  should  always  be  shod  with  flat 
shoes,  rather  broad  at  the  heel  and  without  calks,  and  with- 
out cutting  away  any  of  the  frog,  so  that  a portion  of  the 
wTeight  shall  come  upon  the  frog,  whenever  the  animal 
treads  upon  an  even  surface.  It  is  a rare  occurrence  for 
any  of  the  horses  to  become  disabled  by  contracted  feet. 


THE  END. 


INDEX 


A*  PAGE 

A’bertite . 182 

Aneroid  barometer 10 

Angle  of  repose,  definition  of.  ...  20 

Animal  force  and  traffic,  ratio  be- 
tween  114,  115 

Applying  gravel  on  roads 82  to  85 

Applying  stone  on  roads. 89  and  95,  96 
Applying  new  materials  for  re- 
pairs   121  to  136 

Apportionment  of  materials  for 

repairs 135,  136 

Ascending  grades,  resistance  on. . 30 

Asphalt  pavement 171  to  197 

u foundation  for.  177,  178 

Asphaltum 174,  175 

Asphalt  rock 176,  177 

“ heating  the 178,  179 

“ applying  the.. 179  to  181,  189 

Asphaltic  cement 182  to  185 

Asphalt  block  pavement 191,  192 

Asphalt  mixer 188,  189 

Asphalt  pavement,  merits  of.192  to  194 

“ “ price  of 195 

u “ in  New  York 

City 194,  196 

Asphalt  pavement,  patent 190 

“ “ in  Washing- 
ton, D.  C * 195 

Asphalt,  stone  and  wood  pave- 
ments compared . . 197  to  207 

Asphalt  foot-paths,. . . 215  to  218 

Asphaltine.. . . 182 

B. 

Basalt  and  schist 134 

Basaltic  rock  for  ro^ds . 76 


PAGE 

Bastenne  mineral  tar 178 

Belgian  pavement 160  to  162 

Best  pavement  for  streets 2<>7 

Bethell’s  wood  curing  process. . . . 162 

Beton  Coignet 213,  214 

Binding  material 85 

Bitumens 172  to  175 

Bituminous  limestone. . . .174,  176,  177 
Bituminous  limestone  pavement 

176  to  181 

Bituminous  mastic 215  to  217 

Blake’s  stone  crusher 92  to  94 

Block  pavement  of  asphalt. . . .191,  192 
Block  pavements,  objections  to.203,  204 
Brake  and  starter  for  street  cars 

240  to  243 

Brick  pavement 169  to  172 

Brick  footpaths * 219 

Brick  drains 55  to  58 

Broken  stone  road,  ratio  of  draught 

to  weight  on 22 

Broken  stone  footpaths 219  to  221 

Broken  stone  roads 86  to  96 

C. 

Car  brake  and  starter 240  to  243 

Catch  waters 71,  72 

Central  Park,  N.  Y.,  roads 89 

Charcoal  roads 107,  108 

Chicago  pavements 170 

Classification  of  roadg 77 

Cleansing  street  pavements 199 

Cobble  stones 144 

Cobble  stone  pavement 143  to  145 

Common  ro^ds,  fixing  the  line  of . 44 


254 


INDEX, 


PAGE 

Comparative  merits  of  different 


pavements 197  to  207 

Comparison  of  Telford  and  Mac- 
adam roads 98,  99 

Concrete  footpaths 208  to  215 

Concrete,  compacting .............  210 

Concrete,  hand-made 221  to  223 

Concrete,  mill-made 223  to  226 

Concrete  mixer 224  to  226 

Concrete  foundation  for  roads.  103,  104 

Concrete  of  Rosendale  cement 63 

Contour  lines 17 

Convenience,  relative,  of  street 

pavements 199  to  201 

Construction  of  street  railways 

232  to  240 

Covering  for  roads 76  to  108 

Corduroy  roads 79,  80 


Cost  of  stone,  brick,  and  tile  drains 

57,  59 

Cost,  relative,  of  street  pavements 

198,199 

Cost  of  asphalt  pavements..  195 

Creosoting  wood : 162,  16-3 

Cross  section  of  road  surface 70 

Cross  sections  of  route 17 

Cross  drains  of  roads 55  to  60 

Cross  ties  and  stringers 234  to  236 

Crozier  car  brake  and  starter. 

240  to  243 

Cuba  asphalt 174,  182 

Cubical  block  pavement,  tractive 

force  on 23 

Culverts 60  to  66 

Culverts  of  concrete 62,  66 

Cumberland  road 69 

Curves  of  tonnage  and  wear.  132  to  135 

Curbstones  in  New  York  city 150 

Cuttings,  side  slopes  in 40 

Cylindrical  broom 119  to  121 

“ road  roller S3,  34 

D. 

Dead  Sea  asphaltnm 174 

Decay  of  wood,  protection  against 

162, 163 

Descending  grades,  resistance  on . 30 

Descriptive  memoir, .............  13 


PAGE 

Dimensions  of  stone  blocks  for 

paving 152,  159,  160 

Doloritic  rock  for  roads 76 

Drainage  of  road  surface. . .58  to  60,  71 

“ “ street  railways 232 

“ “ side  slopes  in  cuttings 

41,  42 

Drainage  of  road  bed 55  to  59,  104 

Drains  of  stone,  brick,  and  tiles . 56  to  59 

Drains,  side 53  to  55 

Durability,  relative,  of  street  pave- 
ments   .197,  198 

Dynamical  resistances 29 

E. 

Earth  roads  .........  77,  78 

Earth  road,  ratio  of  draught  to 

weight  on . .22,  23 

Earthwork,  definition  of 40 

Economy  of  thorough  road  main- 
tenance  .109  to  115 

Embankments,  and  their  slopes.44  to  48 
Endurance,  relative,  of  pavements 

197,198 

Excavated  earth,  growth  of. 36 

“ u moving  of 37 

Excavations  35  to  44 

Exhalations,  noxious 203  to  205 

Expediency  considered  in  locating 
a road. 14,  15 

F. 

Fastenings  for  street  railways.237  to  240 

Feklspathic  rock  for  roads 76 

Fireless  locomotive 242,  244 

Flagging  stone  footpaths. 219 

Footpaths .208  to  221 

Footpaths  of  concrete 208  to  215 

“ “ asphalt 215  to  218 

“ “ brick,  etc 219  to  221 

“ “ broken  stone 

Footpaths  in  parks 220,  221 

Form  of  road  surface,  transverse.  70 

Forms  of  street  rails 233,  234 

Fork  for  handling  stone 73 

Foundations  of  concrete.  .103,  104,  147 
u “ rubble  stones  filled 
in  with  concrete. . .105,  106,  107,  149 


INDEX, 


255 


PAGE 

Foundations  of  broken  stone. . . . 143 
“ “ cobble  stones. 143  to  145 

u u rubble  stone.  .100, 101, 

102,  146,  14S 

Foundation  for  asphalt  pavement 

177,178 

Fonssagrives  on  street  pavements 

202,  260 

French  methods  of  maintaining 

roads 117  to  136 

French  roads,  four  classes  of 69 


G. 

Gaujac  tar 173 

Grades,  maximum  and  minimum.  27 

Grades,  definition  of 20 

Grades,  undulating 25 

Grades  at  curves 27 

Grades,  statical  resistance  on 27 

Grades  on  earth  roads 77,  78 

Grahamite 182 

Gravel  footpaths 219  to  221 

Gravel  road,  relation  of  draught  to 

weight  on 22 

Gravel  roads 81  to  86 

“ “ maintenance  of 136 

Growth  of  excavated  earth 36 

il  “ “ rock  (Traut- 

wine) 37 

Quidet  pavement 156,  158 

Gutter  stones  in  New  York  city. . 150 


H. 

Hammers  for  breaking  stone.  .72  to  73 

Hand-made  concrete 221  to  223 

Hardness  of  stone,  how  tested..  .90,  91 
Haywood,  Wm.,  on  street  pave- 
ments  199,  200 

Healthfulness,  relative,  of  street 

pavements 201  to  206 

Heater  for  sand  187,  188 

Heating  asphalt  rock 178,  179 

High  gate- Arch  way  road.  .103,  104,  105 

Hill-side  road 47 

Ilollyhead  road 69 

Hygienic  considerations  touching 
street  pavements. 201^  20C> 


A*  PAGE 

Implements  for  road  making.  .72  to  74 

Inclination  of  side  slopes 40 

Instrumental  examination  of  route  16 
Italian  tramways 228,  229 


Jersey  Flats, 


52 


L. 

Law,  Henry  30,  121,  122 

Lead,  definition  of 35 

Leveling  instrument * 74,  75 

Limestone  for  road  coverings 76 

Location,  considerations  govern- 
ing  9,  13 

Locating  line  on  the  ground 40 

Locomotive  without  fire 242 

Longitudinal  inclination  of  roads.  71 


M. 

Macadam  roads,  grade  on 25 

Macadam  roads  seldom  well  kept 

up 115,  116 

Macadam,  86  to  96,  road,  tractive 

force  on 23 

Macneill,  Sir  John 104 

Macneill’s,  Sir  John,  formulae 29 

Machine  brooms 119  to  121 

Maintenance  and  repair  of  roads 

109  to  136 

Maintenance  of  roads  of  moderate 

traffic 117,  128 

Maintenance  of  roads  of  large 

traffic ' 129  to  136 

Maintenance  and  repairs  of  pave- 
ments  198,  199 

Map  of  route. 12,39 

Map  of  contour  lines 17 

Marsh,  roads  over 49  to  52 

Massachusetts  street  railways.243  to  251 

Mastic,  bituminous 215  to  217 

Materials  for  repairs,  apportion- 
ment of. .135  to  136 

Mechanical  car-starter 240,  243 

Memoir,  descriptive 13 

Merits  of  asphalt  pavements  . .192,  19^ 


256 


INDEX. 


PAGE 

Merits  of  street  pavements  com- 
pared  197  to  207 

Mill  for  mixing  concrete 224  to  226 

Minute  repairs,  maintenance  by 

118  to  128 

Mineral  tar 173 

Mixer  for  asphalt 188,  189 

Mixing  asphaltic  cement  and 

powder 186  to  189 

Morin’s  experiments  for  tractive 

force . .21,  22 

Mortar,  compressive  strength  of 

213,  214 

Moving  earth  37,  38 

N. 

New  York  city  asphalt  pavements 

194,  196,  197 

New  York  state  street  railways 

243  to  249 

Nicolson  pavement .163  to  165 

Noisy  pavements,  objections  to.202,  203 
Noxious  exhalations  from  pave- 
ments  203,  205 

O. 

Objections  to  granite  pavements. . 201 

Objections  to  Macadam  roads 98,  99 

Objections  to  Telford  roads 99 

Objections  to  wood  pavements 
202  to  207 

P. 

Parallel  cross  sections 17 

Paris,  asphalt  pavements  in 194 

Park  walks 220,  221 

Patent  asphalt  pavement 190 

Pavements  for  streets. 137  to  207 

“ foundations  of..  .142  to  149 
Pavement  of  cobble  stones.  .143  to  145 

“ “ rubble  stones 146,147 

“ “ stone  blocks. . .151  to  162 

“ “wood. 162  to  170 

“ “ bricks 168,  169,  219 

“ “ asphalt....  171  to  197,  215 

Pavement,  ratio  of  draught  to 
Weight  08,...,;.,,,,,..,,.,,..  22 


PAO! 

Pavement  of  street  railways. 238  to  240 
Pavements  of  wood,  stone,  and 


asphalt  compared 197  to  207 

Periodical  repairs,  maintenance 

by 129  to  136 

Petroline 182 

Plank  road,  force  of  traction  on. . . 23 

Plank  roads 80 

Portland  cement  for  foot  paths 

208  to  215 

Portland  cement  with  sand. . .210,  211 

Portland  cement,  concrete 63,  64 

Powder  for  asphalt  pavements.185, 186 
Pyrimont,  Seyssel,  tar 173 

R. 

Railway  train  resistances 231 

Rammers  for  concrete 210 

■Reconnoissance  of  route.  10 

Refining  asphaltum  183,184 

Relation  of  animal  force  to  traffic 

114,  115 

Repairs  and  maintenance  of  roads 
109  to  136 


Resistance  to  draught  on  grades . . 27 

Resistance  of  vehicles  in  motion. . 29 

Road  between  Lyons  and  Toulouse  127 


Road  from  Tours  to  Caen 128 

Road  covering,  thickness  of.. 84,  94,  97 

Road  coverings 76  to  108 

Road  rollers 83,  84 

Road  materials 76 


Roads  in  the  Dept,  of  the  Loire. . . 131 
Roads  of  the  Dept,  de  la  Sarthe  . . 127 
Roads,  maintenance  and  repairs  of 
109  to  136 


Roads  on  hill  sides 47,  48 

“ over  marshes 49  to  52 

“ “ tidal  marsh 50  to  52 

Roads  of  logs  (corduroy) 79 

“ “ planks  80 

“ “ gravel 81  to  86 

Rock,  side  cuttings  in 44 

Roman  military  roads 69 

Rosendale  cement,  concrete  63 

Rubble  stone  foundation 100,  101 


Russ  pavement  158,  159,  160 


tNDM. 


25* 


PAGE 

Sand  heater 187,  188 

Schillinger  pavement 212,  213 

Screening  gravel . 82 

Sections  of  line. 12,  39 

Seely’s  wood  curing  process 163 

Seyssel  asphalt  rock 176,  216 

Sewers  .. 137  to  139 

Shell  roads 107 

Shortest  line  seldom  practicable  . . 14 

Side  cuttings,  definition  of 53 

Side  drains,  covered 54,  59 

Side  drains  of  roads 53,  54 

Sidegutters 58,  149  to  150 

Side  slopes  in  cuttings,  inclination 

of 40 

Side  slopes  in  cuttings,  drainage  of  41 

u u “ rock 44 

Sidewalks. 68,  69, 149  to  151,  208  to  221 

Sidewalk  vaults 217,  218 

Sienitic  granite 76 

Silt  basins 59,  60 

Slides.. 43,  44 

Slopes  of  embankments 46 

Sluice-gate  drainage. 51,  52 

Specifications 40 

Spoil  banks,  definition  of. 53 

Springs  in  side  basins 41,  42 


Starter  for  street  cars,  mechanical 


240  to  243 

Statical  resistance  on  grades 27 

Statistics  of  street  railways.  .245  to  252 
Steep  grades,  pavements  on.  153,  155, 

156 

Stone  block  pavement 151  to  162 

Stone  drains 57  to  59 

Stone  trackway  tractive  force 23 

Stone  suitable  for  roads 76 

Stone,  examination  and  tests  of.. 90,  91 

Stone  crusher 92  to  94 

Stone,  wood,  and  asphalt  pave- 
ments compared 197  to  207 

Stowe  pavement 165,  166 

Street  pavements 137  to  207 

“ “ foundations  of 

142  to  149 

Streets,  drainage  of 139,  140 

Street  railways 231  to  252 

Street  rails,  forms  of 283,  234 


PAGE 

Street  railway  stringers  and  cross- 
ties  234  to  236 

Street  railway  fastenings  and  pave- 
ments   237  to  240 

Street  railway  statistics.  . . .243  to  251 
Sub-pavement,  Telford’s.. . . .98  to  100 

Surveys 12 

Surface  drainage  of  roads 58,  59 

Swamps,  roads  over 49,  50 

Sweeping  roads * . . .118  to  121 


T. 

Table  of  resistances  on  various 

grades 30 

Tehuantepec  asphalt 183 

Teil  hydraulic  lime 212,  213 

Thickness  of  broken  stone  covering  94 

“ “ gravel  covering 84 

Telford  road,  tractive  force  on ... . 23 

c<  “ grade  on 25 

Telford  roads 96  to  100 

Telford  sub-pavement 98,  99 

Testing  stone  for  roads .90,  91 

Tidal  marshes 50  to  52 

Tile  drains 56  to  59 

Tonnage  and  wear 132  to  134 

Tools 72  to  75 

Toughness  of  stone,  how  tested  .90,  91 

Topography  by  contour  lines 17 

Tractive  force,  definition  of ..... . 21 

“ “ Morin’s  experi- 
ments on 21,  22 

Tractive  force  in  pounds  per  ton 

on  various  roads 23 

Tramways 227  to  231 

Tramways  in  Italy 228,  229 

Transporting  earth 37,  38 

Transverse  form  of  road  surface  . . 70 

Trial  lines 12 

Trinidad  asphaltum 174,  182,  183 

Turnpike  system 109 


U. 

Undulating  grades.  - . 25 

V. 

Val-d e-Travers 176,  216 


INDEX, 


358 


PAGE 

Varieties  of  bitumen 172  to  175 

Vaults  under  sidewalks 217,  218 


W 

Washington,  D.  C.,  asphalt  pave- 
ments   195 

Wear  of  asphalt  pavement 194 

Wear  to  tonnage,  ratio  of. . . . 132  to  135 

West  Virginia  asphaltum 174,  182 

Whitworth’s  machine  broom 119 


PAGE 

Width  of  country  roads.  66  to  71 

Width  of  French  roads ...  69 

Wings  of  country  roads 70,  95,  96 

Wood,  creosoting 162 

Wood  for  road  coverings 76 

Wood,  stone,  and  asphalt  pave- 
ments compared 197  to  207 

Wooden  culverts 63 

Wooden  pavements .162  to  170 


Wooden  pavements  of  Chicago.. . . 168 
Wooden  pavements,  dust  from.205, 620 


